diff --git a/lib/workingsetcache/cache.go b/lib/workingsetcache/cache.go
index a6091ef51f..c56dccd71b 100644
--- a/lib/workingsetcache/cache.go
+++ b/lib/workingsetcache/cache.go
@@ -131,14 +131,14 @@ func (c *Cache) runWatchers(expireDuration time.Duration) {
 func (c *Cache) expirationWatcher(expireDuration time.Duration) {
 	expireDuration += timeJitter(expireDuration / 10)
 	t := time.NewTicker(expireDuration)
+	defer t.Stop()
+	var csCurr, csPrev fastcache.Stats
 	for {
 		select {
 		case <-c.stopCh:
-			t.Stop()
 			return
 		case <-t.C:
 		}
-
 		c.mu.Lock()
 		if atomic.LoadUint32(&c.mode) != split {
 			// Stop the expirationWatcher on non-split mode.
@@ -148,16 +148,52 @@ func (c *Cache) expirationWatcher(expireDuration time.Duration) {
 		// Reset prev cache and swap it with the curr cache.
 		prev := c.prev.Load().(*fastcache.Cache)
 		curr := c.curr.Load().(*fastcache.Cache)
+		csCurr.Reset()
+		curr.UpdateStats(&csCurr)
+		csPrev.Reset()
+		prev.UpdateStats(&csPrev)
 
 		c.prev.Store(curr)
 
-		var cs fastcache.Stats
-		prev.UpdateStats(&cs)
-		updateCacheStatsHistory(&c.csHistory, &cs)
+		prevGetCalls := csCurr.GetCalls
+		updateCacheStatsHistory(&c.csHistory, &csPrev)
 
 		prev.Reset()
 		c.curr.Store(prev)
 		c.mu.Unlock()
+
+		// Watch for the usage of the prev cache and drop it whenever it receives
+		// less than 5% of get calls comparing to the curr cache.
+		// This allows saving memory.
+		prev, curr = curr, prev
+		checkInterval := 10 * time.Second
+		checkerT := time.NewTicker(checkInterval)
+		checkerDeadline := time.Now().Add(expireDuration - checkInterval)
+		for time.Now().Before(checkerDeadline) {
+			select {
+			case <-c.stopCh:
+				break
+			case <-checkerT.C:
+			}
+			c.mu.Lock()
+			if atomic.LoadUint32(&c.mode) != split {
+				// Do nothing in non-split mode.
+				c.mu.Unlock()
+				break
+			}
+			csCurr.Reset()
+			curr.UpdateStats(&csCurr)
+			csPrev.Reset()
+			prev.UpdateStats(&csPrev)
+			getCalls := csPrev.GetCalls - prevGetCalls
+			if float64(getCalls) < 0.05*float64(csCurr.GetCalls) {
+				// The majority of requests are served from the curr cache,
+				// so the prev cache can be deleted.
+				prev.Reset()
+				break
+			}
+		}
+		checkerT.Stop()
 	}
 }