diff --git a/src/main/java/org/eolang/jeo/representation/XmirRepresentation.java b/src/main/java/org/eolang/jeo/representation/XmirRepresentation.java
index b5e650fb2..a3ca212da 100644
--- a/src/main/java/org/eolang/jeo/representation/XmirRepresentation.java
+++ b/src/main/java/org/eolang/jeo/representation/XmirRepresentation.java
@@ -210,7 +210,13 @@ private static Node open(final Path path) {
 
     /**
      * Optimized schema for XMIR.
+     * It is an optimized version of {@link org.eolang.parser.Schema} class.
      * @since 0.6
+     * @todo #889:30min Use the `Schema` class instead of `OptimizedSchema`.
+     *  The `OptimizedSchema` class is a temporary solution to avoid the performance
+     *  issues with the `Schema` class. We will be able to remove this class after
+     *  the following issue is resolved:
+     *  https://github.com/jcabi/jcabi-xml/issues/277
      */
     private static class OptimizedSchema {
         /**
diff --git a/src/main/java/org/eolang/jeo/representation/xmir/XmlNode.java b/src/main/java/org/eolang/jeo/representation/xmir/XmlNode.java
index db3570ef0..2ce640f66 100644
--- a/src/main/java/org/eolang/jeo/representation/xmir/XmlNode.java
+++ b/src/main/java/org/eolang/jeo/representation/xmir/XmlNode.java
@@ -43,7 +43,13 @@
 public final class XmlNode {
 
     /**
-     * Parent node.
+     * XML node.
+     * Attention!
+     * Here we use the {@link Node} class instead of the {@link com.jcabi.xml.XML}
+     * by performance reasons.
+     * In some cases {@link Node} 10 times faster than {@link com.jcabi.xml.XML}.
+     * You can read more about it here:
+     * <a href="https://github.com/objectionary/jeo-maven-plugin/pull/924">Optimization</a>
      */
     private final Node node;
 
@@ -57,7 +63,7 @@ public XmlNode(final String xml) {
 
     /**
      * Constructor.
-     * @param parent Parent node.
+     * @param parent Xml node.
      */
     public XmlNode(final Node parent) {
         this.node = parent;
diff --git a/src/main/java/org/eolang/jeo/representation/xmir/XmlProgram.java b/src/main/java/org/eolang/jeo/representation/xmir/XmlProgram.java
index b14858596..30afab904 100644
--- a/src/main/java/org/eolang/jeo/representation/xmir/XmlProgram.java
+++ b/src/main/java/org/eolang/jeo/representation/xmir/XmlProgram.java
@@ -43,6 +43,11 @@ public final class XmlProgram {
 
     /**
      * Root node.
+     * Here we use the {@link Node} class instead of the {@link com.jcabi.xml.XML}
+     * by performance reasons.
+     * In some cases {@link Node} 10 times faster than {@link com.jcabi.xml.XML}.
+     * You can read more about it here:
+     * <a href="https://github.com/objectionary/jeo-maven-plugin/pull/924">Optimization</a>
      */
     private final Node root;
 
diff --git a/src/test/java/org/eolang/jeo/representation/XmirRepresentationTest.java b/src/test/java/org/eolang/jeo/representation/XmirRepresentationTest.java
index 89a5bcd07..a9ce9d879 100644
--- a/src/test/java/org/eolang/jeo/representation/XmirRepresentationTest.java
+++ b/src/test/java/org/eolang/jeo/representation/XmirRepresentationTest.java
@@ -161,9 +161,6 @@ void failsToOpenBrokenXmirRepresentationFromFile(@TempDir final Path dir) throws
      * This is a performance test, which is disabled by default.
      * It is used to measure the performance of the conversion of the EO object
      * into the bytecode representation and back.
-     * 1) Timings before the optimization were: 21s, 23s, 21s, 21s (500 attempts)
-     * 2) `XMLDocument` -> `org.w3c.Node` optimization: 11s, 10s, 11s, 10s (500 attempts)
-     * 3) Remove `XMLDocument` usage: 10s, 9s, 9s, 9s (500 attempts)
      */
     @Test
     @Disabled