diff --git a/src/lib/analyzeOscillator.test.ts b/src/lib/analyzeOscillator.test.ts
index ad8dd92..3250adb 100644
--- a/src/lib/analyzeOscillator.test.ts
+++ b/src/lib/analyzeOscillator.test.ts
@@ -34,5 +34,20 @@ describe("analyzeOscillator", () => {
       [2, 1, 2],
       [0, 2, 0],
     ]);
+
+    expect(
+      result.frequencyMap.data.slice(15, 18).map((row) => row.slice(31, 34))
+    ).toEqual([
+      [0, 1, 0],
+      [1, 2, 1],
+      [0, 1, 0],
+    ]);
+    expect(
+      result.heatMap.data.slice(15, 18).map((row) => row.slice(31, 34))
+    ).toEqual([
+      [-1, 2, -1],
+      [2, 0, 2],
+      [-1, 2, -1],
+    ]);
   });
 });
diff --git a/src/lib/getMap.ts b/src/lib/getMap.ts
index 2284d55..2d6ec99 100644
--- a/src/lib/getMap.ts
+++ b/src/lib/getMap.ts
@@ -55,34 +55,77 @@ export function getMap({
         .map(() => -1)
     );
 
-  const historiesArray = histories.map((h) => h.getArray());
+  const firstBitGrid = histories[0];
+  if (firstBitGrid === undefined) {
+    throw new Error("no history");
+  }
+  const firstBitGridUint32Array = firstBitGrid.asInternalUint32Array();
+  const orUint32Array = or.asInternalUint32Array();
 
-  or.forEachAlive((x, y) => {
-    const states: (0 | 1)[] = [];
-    let heat = 0;
-    let prevCell = historiesArray[0]?.[y][x];
-    for (const h of historiesArray) {
-      const cell = h[y][x];
-      if (prevCell !== undefined && prevCell !== cell) {
-        heat++;
-      }
-      prevCell = cell;
-      states.push(cell);
-      if (cell !== 0) {
-        frequencyArray[y][x]++;
-      }
+  {
+    function getAlive(array: Uint32Array, offset: number, u: number): 0 | 1 {
+      const value = array[offset]!;
+      const alive = (value & (1 << (BITS_MINUS_1 - u))) !== 0 ? 1 : 0;
+      return alive;
     }
 
-    if (
-      historiesArray.length !== 0 &&
-      historiesArray[0][y][x] !==
-        historiesArray[historiesArray.length - 1][y][x]
-    ) {
-      heat++;
+    const width = firstBitGrid.getWidth32();
+    const height = firstBitGrid.getHeight();
+    const BITS = 32;
+    const BITS_MINUS_1 = BITS - 1;
+    for (let i = 0; i < height; i++) {
+      const rowIndex = i * width;
+      for (let j = 0; j < width; j++) {
+        const offset = rowIndex + j;
+        // skip if empty
+        if (orUint32Array[offset] === 0) {
+          continue;
+        }
+        const BITS_J = j * BITS;
+        for (let u = 0; u < BITS; u++) {
+          // skip if dead
+          if (getAlive(orUint32Array, offset, u) === 0) {
+            continue;
+          }
+
+          const x = BITS_J + u;
+          const y = i;
+
+          const states: (0 | 1)[] = [];
+          let heat = 0;
+          const firstCell = getAlive(firstBitGridUint32Array, offset, u);
+          let prevCell = firstCell;
+          let frequency = 0;
+          for (const h of histories) {
+            const array = h.asInternalUint32Array();
+            const cell = getAlive(array, offset, u);
+            if (prevCell !== undefined && prevCell !== cell) {
+              heat++;
+            }
+            prevCell = cell;
+            states.push(cell);
+            if (cell !== 0) {
+              frequency++;
+            }
+          }
+
+          if (
+            firstCell !==
+            getAlive(
+              histories[histories.length - 1]!.asInternalUint32Array(),
+              offset,
+              u
+            )
+          ) {
+            heat++;
+          }
+          heatArray[y][x] = heat;
+          periodArray[y][x] = findPeriod(states);
+          frequencyArray[y][x] = frequency;
+        }
+      }
     }
-    heatArray[y][x] = heat;
-    periodArray[y][x] = findPeriod(states);
-  });
+  }
 
   const periodCountMap = getCountMap(periodArray);
   periodCountMap.delete(0);
@@ -96,27 +139,22 @@ export function getMap({
   return {
     periodMap: {
       data: periodArray,
-      list: mapUnique(periodArray).filter((x) => x !== 0),
+      list: [...periodCountMap.keys()].sort((a, b) => a - b),
       countMap: periodCountMap,
     },
     frequencyMap: {
       data: frequencyArray,
-      list: mapUnique(frequencyArray).filter((x) => x !== 0),
+      list: [...frequencyCountMap.keys()].sort((a, b) => a - b),
       countMap: frequencyCountMap,
     },
     heatMap: {
       data: heatArray,
-      list: mapUnique(heatArray).filter((x) => x !== -1),
+      list: [...heatCountMap.keys()].sort((a, b) => a - b),
       countMap: heatCountMap,
     },
   };
 }
 
-function mapUnique(map: number[][]): number[] {
-  const set = new Set(map.flat());
-  return [...set].sort((a, b) => a - b);
-}
-
 function getCountMap(map: number[][]): Map<number, number> {
   const countMap = new Map<number, number>();
   for (const row of map) {