diff --git a/nullboard.html b/nullboard.html
index 6331eeb..592ba8b 100644
--- a/nullboard.html
+++ b/nullboard.html
@@ -1338,19 +1338,70 @@
             this.databases.push(arguments[i]);
          }
          this.deltas = new Deltas(this.cache());
-         this.intervals = [];
          this.scheduleSync();
-         this.syncCacheWithPrimary();
+         this.syncIntervalCacheWithPrimary();
       }
 
-      syncCacheWithPrimary()
+      redundantSyncInterval(key)
+      {
+         let last_run = this.intervals_last_run[key];
+         let now = Date.now();
+         let redundant = last_run != undefined && now - last_run < 1000;
+         console.log(`redundant ${key}? last=${last_run}, now=${now}, redundant=${redundant}`);
+         if (!redundant)
+            this.intervals_last_run[key] = now;
+         return redundant;
+      }
+
+      syncIntervalDeltas()
+      {
+         if (!this.redundantSyncInterval("syncIntervalDeltas"))
+            return;
+         this._syncIntervalDeltas();
+      }
+
+      _syncIntervalDeltas()
+      {
+         var n = this.pendingSyncCount();
+         try
+         {
+            this.deltas.popEach((key) => {
+               console.log("syncing: " + key);
+               this.replicate(key);
+            });
+         }
+         catch (e)
+         {
+            console.log("failed to sync: " + e);
+         }
+         finally
+         {
+            this.writePendingSyncCount();
+         }
+      }
+
+      syncIntervalCacheWithPrimary()
+      {
+         if (!this.redundantSyncInterval("syncIntervalCacheWithPrimary"))
+            return;
+         this._syncIntervalCacheWithPrimary();
+      }
+
+      _syncIntervalCacheWithPrimary()
       {
          if (this.pendingSyncCount())
             return;
          this.syncAWithB(this.cache(), this.primary());
       }
 
-      syncReplicasWithCache()
+      syncIntervalReplicasWithCache()
+      {
+         if (!this.redundantSyncInterval("syncIntervalReplicasWithCache"))
+            return;
+         this._syncIntervalReplicasWithCache();
+      }
+
+      _syncIntervalReplicasWithCache()
       {
          this.replicas().slice(1).forEach((replica) => {
             this.syncAWithB(replica, this.cache());
@@ -1383,43 +1434,26 @@
 
       scheduleSync()
       {
+         this.close();
          this.intervals.push(
-            setInterval(() => { this.syncDeltas(); }, 10 * 1000)
+            setInterval(() => { this.syncIntervalDeltas(); }, 10 * 1000)
          );
          this.intervals.push(
-            setInterval(() => { this.syncCacheWithPrimary(); }, 120 * 1000)
+            setInterval(() => { this.syncIntervalCacheWithPrimary(); }, 120 * 1000)
          );
          this.intervals.push(
-            setInterval(() => { this.syncReplicasWithCache(); }, 123 * 1000)
+            setInterval(() => { this.syncIntervalReplicasWithCache(); }, 123 * 1000)
          );
       }
 
       close()
       {
-         this.intervals.forEach((i) => {
-            clearInterval(i);
-         });
-         this.intervals = [];
-      }
-
-      syncDeltas()
-      {
-         var n = this.pendingSyncCount();
-         try
-         {
-            this.deltas.popEach((key) => {
-               console.log("syncing: " + key);
-               this.replicate(key);
+         if (this.intervals)
+            this.intervals.forEach((i) => {
+               clearInterval(i);
             });
-         }
-         catch (e)
-         {
-            console.log("failed to sync: " + e);
-         }
-         finally
-         {
-            this.writePendingSyncCount();
-         }
+         this.intervals = [];
+         this.intervals_last_run = {};
       }
 
       pendingSyncCount()