diff --git a/h2/src/main/org/h2/mvstore/FileStore.java b/h2/src/main/org/h2/mvstore/FileStore.java
index 957ed056c4..949736503a 100644
--- a/h2/src/main/org/h2/mvstore/FileStore.java
+++ b/h2/src/main/org/h2/mvstore/FileStore.java
@@ -423,7 +423,7 @@ public final void setAutoCommitDelay(int millis) {
                 stopBackgroundThread(millis >= 0);
                 // start the background thread if needed
                 if (millis > 0 && mvStore.isOpen()) {
-                    int sleep = Math.max(1, millis / 10);
+                    int sleep = Math.max(10, millis / 3);
                     BackgroundWriterThread t = new BackgroundWriterThread(this, sleep, toString());
                     if (backgroundWriterThread.compareAndSet(null, t)) {
                         t.start();
@@ -622,7 +622,7 @@ protected final boolean hasPersistentData() {
     }
 
     protected final boolean isIdle() {
-        return autoCompactLastFileOpCount == getWriteCount() + getReadCount();
+        return autoCompactLastFileOpCount >= getWriteCount() + getReadCount();
     }
 
     protected final void setLastChunk(C last) {
@@ -1835,7 +1835,8 @@ void writeInBackground() {
                     mvStore.tryCommit();
                 }
                 doHousekeeping(mvStore);
-                autoCompactLastFileOpCount = getWriteCount() + getReadCount();
+                // less than 10 I/O operations will still count as "idle"
+                autoCompactLastFileOpCount = getWriteCount() + getReadCount() + 10;
             }
         } catch (InterruptedException ignore) {
         } catch (Throwable e) {
diff --git a/h2/src/main/org/h2/mvstore/FreeSpaceBitSet.java b/h2/src/main/org/h2/mvstore/FreeSpaceBitSet.java
index f0fff58cc1..23fd5512bb 100644
--- a/h2/src/main/org/h2/mvstore/FreeSpaceBitSet.java
+++ b/h2/src/main/org/h2/mvstore/FreeSpaceBitSet.java
@@ -145,10 +145,8 @@ private int allocate(int blocks, int reservedLow, int reservedHigh, boolean allo
             int freeBlocks = end - start;
             if (end < 0 || freeBlocks >= blocks) {
                 if ((reservedHigh < 0 || start < reservedHigh) && start + blocks > reservedLow) { // overlap detected
-                    if (reservedHigh < 0) {
-                        start = getAfterLastBlock();
-                        end = -1;
-                    } else {
+                    if (reservedHigh >= 0) {
+                        freeBlocksTotal += freeBlocks;
                         i = reservedHigh;
                         continue;
                     }
diff --git a/h2/src/main/org/h2/mvstore/RandomAccessStore.java b/h2/src/main/org/h2/mvstore/RandomAccessStore.java
index e69737f45d..745e3b2af7 100644
--- a/h2/src/main/org/h2/mvstore/RandomAccessStore.java
+++ b/h2/src/main/org/h2/mvstore/RandomAccessStore.java
@@ -703,15 +703,17 @@ private void shrinkIfPossible(int minPercent) {
     @Override
     protected void doHousekeeping(MVStore mvStore) throws InterruptedException {
         boolean idle = isIdle();
+        int rewritableChunksFillRate = getRewritableChunksFillRate();
         if (idle && stopIdleHousekeeping) {
             return;
         }
         int autoCommitMemory = mvStore.getAutoCommitMemory();
-        int fillRate = getFillRate();
-        if (isFragmented() && fillRate < getAutoCompactFillRate()) {
+        int fileFillRate = getFillRate();
+        long chunksTotalSize = size() * fileFillRate / 100;
+        if (isFragmented() && fileFillRate < getAutoCompactFillRate()) {
             mvStore.tryExecuteUnderStoreLock(() -> {
                 int moveSize = 2 * autoCommitMemory;
-                if (isIdle()) {
+                if (idle) {
                     moveSize *= 4;
                 }
                 compactMoveChunks(101, moveSize, mvStore);
@@ -719,29 +721,35 @@ protected void doHousekeeping(MVStore mvStore) throws InterruptedException {
             });
         }
 
-        int chunksFillRate = getRewritableChunksFillRate();
-        int adjustedChunksFillRate = 100 - (100 - chunksFillRate) / 2;
-        int fillRateToCompare = isIdle() ? chunksFillRate : adjustedChunksFillRate;
-        if (fillRateToCompare < getTargetFillRate()) {
+        int chunksFillRate = getChunksFillRate();
+        int adjustedUpFillRate = 50 + rewritableChunksFillRate / 2;
+        int fillRateToCompare = idle ? rewritableChunksFillRate : adjustedUpFillRate;
+        if (fillRateToCompare < getTargetFillRate(idle)) {
+            int targetFillRate = idle ? adjustedUpFillRate : rewritableChunksFillRate;
             mvStore.tryExecuteUnderStoreLock(() -> {
                 int writeLimit = autoCommitMemory;
-                if (!isIdle()) {
+                if (!idle) {
                     writeLimit /= 4;
                 }
-                if (rewriteChunks(writeLimit, isIdle() ? adjustedChunksFillRate : chunksFillRate)) {
+                if (rewriteChunks(writeLimit, targetFillRate)) {
                     dropUnusedChunks();
                 }
                 return true;
             });
         }
-        stopIdleHousekeeping = idle && getFillRate() <= fillRate && getRewritableChunksFillRate() <= chunksFillRate;
+        stopIdleHousekeeping = false;
+        if (idle) {
+            int currentChunksFillRate = getChunksFillRate();
+            long currentTotalChunksSize = size() * getFillRate() / 100;
+            stopIdleHousekeeping = currentTotalChunksSize > chunksTotalSize || currentTotalChunksSize == chunksTotalSize && currentChunksFillRate <= chunksFillRate;
+      }
     }
 
-    private int getTargetFillRate() {
+    private int getTargetFillRate(boolean idle) {
         int targetRate = getAutoCompactFillRate();
         // use a lower fill rate if there were any file operations since the last time
-        if (!isIdle()) {
-            targetRate /= 2;
+        if (!idle) {
+            targetRate = targetRate * targetRate / 100;
         }
         return targetRate;
     }