diff --git a/Files.cs b/Files.cs
index a738999..88fd7de 100644
--- a/Files.cs
+++ b/Files.cs
@@ -2,30 +2,30 @@ public class DirectoryEntry {
     /// <summary>
     /// Initializer
     /// </summary>
-    public DirectoryEntry(string path, string from) {
+    public DirectoryEntry(string path, string relativePath) {
         fileInfo = new FileInfo(path);
-        relativePath = path.Substring(from.Length + 1);
+        this.relativePath = relativePath;
     }
     public string relativePath;
     public FileInfo fileInfo;
     public Reason reason;
     /// <summary>
     /// Function to search in the destination folder for the same file and compare them
-    /// (<paramref name="destinationList"/>, <paramref name="allExtensions"/>, <paramref name="extensions"/>)
+    /// (<paramref name="destinationDictionary"/>, <paramref name="allExtensions"/>, <paramref name="extensions"/>)
     /// </summary>
-    /// <param name="destinationList">The list of all files in the destination folder</param>
+    /// <param name="destinationDictionary">The dictionaty of all files in the destination folder</param>
     /// <param name="allExtensions">If all extensions have to be checked for content differencies</param>
     /// <param name="extensions">The list of the extensions to check for content differencies</param>
     /// <returns>Returns true if the file has to be copied</returns>
-    public bool ToCopy(ref DirectoryEntry[] destinationList, bool allExtensions, string[] extensions) {
-        Int32 pos;
-        bool found = IsInList(destinationList, out pos);
-        if(!found) {
+    public bool ToCopy(ref Dictionary<string, DirectoryEntry> destinationDictionary, bool allExtensions, string[] extensions) {
+        DirectoryEntry e;
+        try {e = destinationDictionary[relativePath];}
+        catch(Exception) {
+            // Does not exist
             reason = Reason.CopyNotThere;
             return true;
         }
-        DirectoryEntry e = destinationList[pos];
-        destinationList = RemoveAt(destinationList, pos);
+        // Skip if directory
         if((e.fileInfo.Attributes & FileAttributes.Directory) == FileAttributes.Directory) return false;
         // Check size
         if(fileInfo.Length != e.fileInfo.Length) {
@@ -57,46 +57,20 @@ public bool ToCopy(ref DirectoryEntry[] destinationList, bool allExtensions, str
     }
     /// <summary>
     /// Function to know of a file has to be removed
-    /// (<paramref name="sourceList"/>)
+    /// (<paramref name="sourceDictionary"/>)
     /// </summary>
-    /// <param name="sourceList">The list of files in the source folder</param>
+    /// <param name="sourceDictionary">The dictionary of files in the source folder</param>
     /// <returns>Returns true if the file has to be removed</returns>
-    public bool ToRemove(DirectoryEntry[] sourceList) {
-        bool toRemove = !IsInList(sourceList, out _);
-        if(toRemove) reason = Reason.Remove;
-        return toRemove;
-    }
-    /// <summary>
-    /// Function to search a file in a list of files
-    /// (<paramref name="list"/>, <paramref name="pos"/>)
-    /// </summary>
-    /// <param name="list">The list of files</param>
-    /// <param name="pos">The returned position</param>
-    /// <returns>Returns true if the file is in the list</returns>
-    private bool IsInList(DirectoryEntry[] list, out Int32 pos) {
-        Int32 length = list.Length;
-        for(pos = 0; pos < length; pos++) {
-            if(relativePath == list[pos].relativePath) return true;
+    public bool ToRemove(ref Dictionary<string, DirectoryEntry> sourceDictionary) {
+        DirectoryEntry e;
+        try {
+            e = sourceDictionary[relativePath];
+            return false;
+        }
+        catch(Exception) {
+            reason = Reason.Remove;
+            return true;
         }
-        return false;
-    }
-    /// <summary>
-    /// Function to search remove an item from a DirectoryEntry array
-    /// (<paramref name="source"/>, <paramref name="index"/>)
-    /// </summary>
-    /// <param name="source">The source DirectoryEntry array</param>
-    /// <param name="index">The index of the item to remove</param>
-    /// <returns>Returns the source array without the item to remove</returns>
-    public static DirectoryEntry[] RemoveAt(DirectoryEntry[] source, Int32 index) {
-        Int32 lenght = source.Length;
-        DirectoryEntry[] dest = new DirectoryEntry[lenght - 1];
-        if( index > 0 )
-            Array.Copy(source, 0, dest, 0, index);
-
-        if( index < lenght - 1 )
-            Array.Copy(source, index + 1, dest, index, lenght - index - 1);
-
-        return dest;
     }
 }
 
diff --git a/Logger.cs b/Logger.cs
index b455005..a45da66 100644
--- a/Logger.cs
+++ b/Logger.cs
@@ -4,7 +4,8 @@ public class Logger {
     private static string barFull = "█", barEmpty = " ";
     private static string? logfilename;
     private static StreamWriter? logstream;
-    private static Task? logTask;
+    private static List<Task> logTasks = new List<Task>();
+    private static int ticket = 0;
     /// <summary>
     /// Function to initialize the file logging
     /// (<paramref name="log"/>)
@@ -30,8 +31,9 @@ public static void ReinitializeLogging() {
     /// </summary>
     public static async void TerminateLogging() {
         if(logstream != null) {
-            if(logTask != null) await logTask;
+            if(logTasks.Count != 0) await logTasks[logTasks.Count - 1];
             logstream.Close();
+            logTasks = new List<Task>();
         }
     }
     /// <summary>
@@ -39,62 +41,79 @@ public static async void TerminateLogging() {
     /// (<paramref name="message"/>)
     /// </summary>
     /// <param name="message">The message to output</param>
-    public static void Success(string message) {
+    public static async void Success(string message) {
+        int t = ticket++;
         string time = TimeString();
-        Console.ForegroundColor = ConsoleColor.DarkGray;
-        Console.Write(time);
-        Console.ForegroundColor = ConsoleColor.Green;
-        Console.Write("(Success) ");
-        Console.ForegroundColor = ConsoleColor.White;
-        Console.WriteLine(message);
-        Console.ResetColor();
-        if(logstream != null) logTask = logstream.WriteLineAsync(time + "(Success) " + message);
+        await logTasks.ElementAt(t);
+        logTasks.Append(Task.Run(() => {
+            Console.ForegroundColor = ConsoleColor.DarkGray;
+            Console.Write(time);
+            Console.ForegroundColor = ConsoleColor.Green;
+            Console.Write("(Success) ");
+            Console.ForegroundColor = ConsoleColor.White;
+            Console.WriteLine(message);
+            Console.ResetColor();
+            if(logstream != null) logstream.WriteLineAsync(time + "(Success) " + message);
+        }));
     }
     /// <summary>
     /// Function to output an info message
     /// (<paramref name="message"/>)
     /// </summary>
     /// <param name="message">The message to output</param>
-    public static void Info(string message) {
-        Console.ForegroundColor = ConsoleColor.DarkGray;
-        Console.Write(TimeString());
-        Console.ForegroundColor = ConsoleColor.Cyan;
-        Console.Write("(Info) ");
-        Console.ForegroundColor = ConsoleColor.White;
-        Console.WriteLine(message);
-        Console.ResetColor();
+    public static async void Info(string message) {
+        int t = ticket++;
+        string time = TimeString();
+        await logTasks.ElementAt(t);
+        logTasks.Append(Task.Run(() => {
+            Console.ForegroundColor = ConsoleColor.DarkGray;
+            Console.Write(time);
+            Console.ForegroundColor = ConsoleColor.Cyan;
+            Console.Write("(Info) ");
+            Console.ForegroundColor = ConsoleColor.White;
+            Console.WriteLine(message);
+            Console.ResetColor();
+        }));
     }
     /// <summary>
     /// Function to output a warning message
     /// (<paramref name="message"/>)
     /// </summary>
     /// <param name="message">The message to output</param>
-    public static void Warning(string message) {
-        string time = TimeString(); 
-        Console.ForegroundColor = ConsoleColor.DarkGray;
-        Console.Write(time);
-        Console.ForegroundColor = ConsoleColor.Yellow;
-        Console.Write("(Warning) ");
-        Console.ForegroundColor = ConsoleColor.White;
-        Console.WriteLine(message);
-        Console.ResetColor();
-        if(logstream != null) logTask = logstream.WriteLineAsync(time + "(Warning) " + message);
+    public static async void Warning(string message) {
+        int t = ticket++;
+        string time = TimeString();
+        await logTasks.ElementAt(t);
+        logTasks.Append(Task.Run(() => {
+            Console.ForegroundColor = ConsoleColor.DarkGray;
+            Console.Write(time);
+            Console.ForegroundColor = ConsoleColor.Yellow;
+            Console.Write("(Warning) ");
+            Console.ForegroundColor = ConsoleColor.White;
+            Console.WriteLine(message);
+            Console.ResetColor();
+            if(logstream != null) logstream.WriteLineAsync(time + "(Warning) " + message);
+        }));
     }
     /// <summary>
     /// Function to output an error message
     /// (<paramref name="message"/>)
     /// </summary>
     /// <param name="message">The message to output</param>
-    public static void Error(string message) {
+    public static async void Error(string message) {
+        int t = ticket++;
         string time = TimeString();
-        Console.ForegroundColor = ConsoleColor.DarkGray;
-        Console.Write(time);
-        Console.ForegroundColor = ConsoleColor.Red;
-        Console.Write("(Error) ");
-        Console.ForegroundColor = ConsoleColor.White;
-        Console.WriteLine(message);
-        Console.ResetColor();
-        if(logstream != null) logTask = logstream.WriteLineAsync(time + "(Error) " + message);
+        await logTasks.ElementAt(t);
+        logTasks.Append(Task.Run(() => {
+            Console.ForegroundColor = ConsoleColor.DarkGray;
+            Console.Write(time);
+            Console.ForegroundColor = ConsoleColor.Red;
+            Console.Write("(Error) ");
+            Console.ForegroundColor = ConsoleColor.White;
+            Console.WriteLine(message);
+            Console.ResetColor();
+            if(logstream != null) logstream.WriteLineAsync(time + "(Error) " + message);
+        }));
     }
     /// <summary>
     /// Function to clear the last console line
diff --git a/Makefile b/Makefile
index 6e87dd6..4c30448 100644
--- a/Makefile
+++ b/Makefile
@@ -24,4 +24,5 @@ run-dotnet-debug:
 > dotnet ./transfer/docker/debug/backup-utility.dll -- -s test/source -d test/destination -r test/removed -t 100 -e extensions.txt -l -b
 
 run-dotnet-release:
-> ./transfer/docker/release/linux-x64/backup-utility
\ No newline at end of file
+> dotnet publish -c debug
+> ./transfer/docker/release/linux-x64/backup-utility -s test/source -d test/destination -r test/removed -l
\ No newline at end of file
diff --git a/Program.cs b/Program.cs
index f48d862..223d9e8 100644
--- a/Program.cs
+++ b/Program.cs
@@ -2,14 +2,16 @@
 using System.IO.Compression;
 
 public class Program {
-    static void Main(string[] args) {
+    private static Arguments arguments = new Arguments();
+    private static EnumerationOptions enumOptions = new EnumerationOptions();
+    static async Task Main(string[] args) {
         // Version
         string version = "1.5.6";
         // Lists
         string[] sourceList = new string[0], destinationList = new string[0], extensionList = new string[0];
-        DirectoryEntry[] sourceInfoList = new DirectoryEntry[0], destinationInfoList = new DirectoryEntry[0],
-            toCopyList = new DirectoryEntry[0], toRemoveFileList = new DirectoryEntry[0], toRemoveFolderList = new DirectoryEntry[0];
-        EnumerationOptions enumOptions = new EnumerationOptions();
+        Dictionary<string, DirectoryEntry> sourceInfoDictionary = new Dictionary<string, DirectoryEntry>();
+        Dictionary<string, DirectoryEntry> destinationInfoDictionary = new Dictionary<string, DirectoryEntry>();
+        DirectoryEntry[] toCopyList = new DirectoryEntry[0], toRemoveFileList = new DirectoryEntry[0], toRemoveFolderList = new DirectoryEntry[0];
         enumOptions.RecurseSubdirectories = true; enumOptions.AttributesToSkip = default;
         // Other variables
         Int32 length, filesToCopy, filesCopied, foldersToCopy, foldersCopied,
@@ -18,7 +20,6 @@ static void Main(string[] args) {
         Int64 timestamp;
         string backupFolder = "";
         // Parsing arguments
-        Arguments arguments = new Arguments();
         try {
             arguments.Parse(args);
             if(arguments.help) return;
@@ -107,7 +108,7 @@ static void Main(string[] args) {
         else {
             Logger.Info("Extension list not set, only file size will be used to compare files");
         }
-        //Compressed Backup
+        // Compressed Backup
         if(arguments.backup) {
             Logger.Info("Compressed backup: yes");
             backupFolder = arguments.destination + "-backups";
@@ -129,62 +130,30 @@ static void Main(string[] args) {
             // Timestamp
             timestamp = new DateTimeOffset(DateTime.UtcNow).ToUnixTimeSeconds() + arguments.time;
             // Scan folders
-            Logger.Info("Starting source folder scan...");
-            try {
-                sourceList = Directory.EnumerateFileSystemEntries(arguments.source, "*", enumOptions).ToArray();
-                Logger.Success("Source folder scanned: " + sourceList.Length + " items found");
-            }
-            catch(Exception e) {
-                Logger.Error("Error while scanning source folder: " + e);
-                continue;
-            }
-            Logger.Info("Starting destination folder scan...");
-            try {
-                destinationList = Directory.EnumerateFileSystemEntries(arguments.destination, "*", enumOptions).ToArray();
-                Logger.Success("Destination folder scanned: " + destinationList.Length + " items found");
-            }
-            catch(Exception e) {
-                Logger.Error("Error while scanning destination folder: " + e);
-                continue;
-            }
+            Task<string[]> sourceTask = scanFolder(arguments.source, true);
+            Task<string[]> destinationTask = scanFolder(arguments.destination, false);
+            sourceList = await sourceTask;
+            destinationList = await destinationTask;
             // Build file info
-            Logger.Info("Building source file info list...");
-            try {
-                foreach(string item in sourceList) {
-                    sourceInfoList = sourceInfoList.Append(new DirectoryEntry(item, arguments.source)).ToArray();
-                }
-                Logger.Success("Source file info list built");
-            }
-            catch(Exception e) {
-                Logger.Error("Error while building source file info list: " + e);
-                continue;
-            }
+            Task<Dictionary<string, DirectoryEntry>> sourceDictionaryTask = buildInfoDictionary(sourceList, arguments.source, true);
+            Task<Dictionary<string, DirectoryEntry>> destinationDictionaryTask = buildInfoDictionary(sourceList, arguments.destination, false);
+            sourceInfoDictionary = await sourceDictionaryTask;
+            destinationInfoDictionary = await sourceDictionaryTask;
             sourceList = new string[0];
-            Logger.Info("Building destination file info list...");
-            try {
-                foreach(string item in destinationList) {
-                    destinationInfoList = destinationInfoList.Append(new DirectoryEntry(item, arguments.destination)).ToArray();
-                }
-                Logger.Success("Destination file info list built");
-            }
-            catch(Exception e) {
-                Logger.Error("Error while building destination file info list: " + e);
-                continue;
-            }
             destinationList = new string[0];
             // Items to copy
             Logger.Info("Determining items to copy...");
-            length = sourceInfoList.Length;
             filesToCopy = 0; foldersToCopy = 0; sizeToCopy = 0;
-            for(Int32 i = 0; i < length; i++) {
-                if(sourceInfoList[i].ToCopy(ref destinationInfoList, arguments.allExtensions, extensionList)) {
-                    toCopyList = toCopyList.Append(sourceInfoList[i]).ToArray();
-                    if((sourceInfoList[i].fileInfo.Attributes & FileAttributes.Directory) == FileAttributes.Directory) {
+            foreach(KeyValuePair<string, DirectoryEntry> entry in sourceInfoDictionary) {
+                DirectoryEntry value = entry.Value;
+                if(value.ToCopy(ref destinationInfoDictionary, arguments.allExtensions, extensionList)) {
+                    toCopyList = toCopyList.Append(value).ToArray();
+                    if((value.fileInfo.Attributes & FileAttributes.Directory) == FileAttributes.Directory) {
                         foldersToCopy++;
                     }
                     else {
                         filesToCopy++;
-                        sizeToCopy += (UInt64)sourceInfoList[i].fileInfo.Length;
+                        sizeToCopy += (UInt64)value.fileInfo.Length;
                     }
                 }
             }
@@ -193,18 +162,18 @@ static void Main(string[] args) {
                 Logger.HumanReadableSize(sizeToCopy) + ")");
             // Items to remove
             Logger.Info("Determining items to remove...");
-            length = destinationInfoList.Length;
             filesToRemove = 0; foldersToRemove = 0; sizeToRemove = 0;
-            for(Int32 i = 0; i < length; i++) {
-                if(destinationInfoList[i].ToRemove(sourceInfoList)) {
-                    if((destinationInfoList[i].fileInfo.Attributes & FileAttributes.Directory) == FileAttributes.Directory) {
-                        toRemoveFolderList = toRemoveFolderList.Append(destinationInfoList[i]).ToArray();
+            foreach(KeyValuePair<string, DirectoryEntry> entry in destinationInfoDictionary) {
+                DirectoryEntry value = entry.Value;
+                if(value.ToRemove(ref sourceInfoDictionary)) {
+                    if((value.fileInfo.Attributes & FileAttributes.Directory) == FileAttributes.Directory) {
+                        toRemoveFolderList = toRemoveFolderList.Append(value).ToArray();
                         foldersToRemove++;
                     }
                     else {
-                        toRemoveFileList = toRemoveFileList.Append(destinationInfoList[i]).ToArray();
+                        toRemoveFileList = toRemoveFileList.Append(value).ToArray();
                         filesToRemove++;
-                        sizeToRemove += (UInt64)destinationInfoList[i].fileInfo.Length;
+                        sizeToRemove += (UInt64)value.fileInfo.Length;
                     }
                 }
             }
@@ -212,7 +181,8 @@ static void Main(string[] args) {
                 filesToRemove.ToString() + " file" + (filesToRemove == 1 ? "" : "s") + " to remove (" +
                 Logger.HumanReadableSize(sizeToRemove) + ")");
             // Clear info lists
-            sourceInfoList = new DirectoryEntry[0]; destinationInfoList = new DirectoryEntry[0];
+            sourceInfoDictionary = new Dictionary<string, DirectoryEntry>();
+            destinationInfoDictionary = new Dictionary<string, DirectoryEntry>();
             // Copy files
             length = toCopyList.Length;
             filesCopied = 0; foldersCopied = 0; sizeCopied = 0;
@@ -364,4 +334,54 @@ static void Main(string[] args) {
             Logger.ReinitializeLogging();
         }
     }
+
+    /// <summary>
+    /// Function to get the list of files in a folder
+    /// (<paramref name="path"/>, <paramref name="type"/>)
+    /// </summary>
+    /// <param name="path">The path</param>
+    /// <param name="type">True if source folder, false if destination folder</param>
+    /// <returns>Returns the task of a string array</returns>
+    public static async Task<string[]> scanFolder(string path, bool type) {
+        return await Task.Run<string[]>(() => {
+            string[] array;
+            Logger.Info("Starting " + (type ? "source" : "destination") + " folder scan...");
+            try {
+                array = Directory.EnumerateFileSystemEntries(arguments.source, "*", enumOptions).ToArray();
+                Logger.Success((type ? "Source" : "Destination") + " folder scanned: " + array.Length + " items found");
+            }
+            catch(Exception e) {
+                Logger.Error("Error while scanning " + (type ? "source" : "destination") + " folder: " + e);
+                Environment.Exit(1);
+                array = new string[0];
+            }
+            return array;
+        });
+    }
+
+    /// <summary>
+    /// Function to get the list of files in a folder
+    /// (<paramref name="path"/>, <paramref name="type"/>)
+    /// </summary>
+    /// <param name="path">The path</param>
+    /// <param name="type">True if source folder, false if destination folder</param>
+    /// <returns>Returns the task of a string array</returns>
+    public static async Task<Dictionary<string, DirectoryEntry>> buildInfoDictionary(string[] list, string path, bool type) {
+        return await Task.Run<Dictionary<string, DirectoryEntry>>(() => {
+            Dictionary<string, DirectoryEntry> dictionary = new Dictionary<string, DirectoryEntry>();
+            Logger.Info("Building " + (type ? "source" : "destination") + " file info list...");
+            try {
+                foreach(string item in list) {
+                    string relativePath = item.Substring(path.Length + 1);
+                    dictionary[relativePath] = new DirectoryEntry(item, relativePath);
+                }
+                Logger.Success((type ? "Source" : "Destination") + " file info list built");
+            }
+            catch(Exception e) {
+                Logger.Error("Error while building " + (type ? "source" : "destination") + " file info list: " + e);
+                Environment.Exit(2);
+            }
+            return dictionary;
+        });
+    }
 }
\ No newline at end of file