diff --git a/blocks/randompruner.go b/blocks/randompruner.go
index 0cfdc13..db24154 100644
--- a/blocks/randompruner.go
+++ b/blocks/randompruner.go
@@ -35,6 +35,11 @@ type RandomPrunerConfig struct {
 	PinDuration time.Duration
 }
 
+type cidStatus struct {
+	pinned  bool
+	pinTime time.Time
+}
+
 // RandomPruner is a blockstore wrapper which removes blocks at random when disk
 // space is exhausted
 type RandomPruner struct {
@@ -48,12 +53,25 @@ type RandomPruner struct {
 
 	// A list of "hot" CIDs which should not be deleted, and when they were last
 	// used
-	pins   map[cid.Cid]time.Time
-	pinsLk sync.Mutex
+	allCids           map[cid.Cid]*cidStatus
+	allCidsLk         sync.Mutex
+	lastAllCidsUpdate time.Time
 
 	pruneLk sync.Mutex
 }
 
+var cidStatusPool = sync.Pool{
+	New: func() any {
+		return new(cidStatus)
+	},
+}
+
+// 128K
+const approxBlockSizeBytes = 1 << 17
+
+// 40 Bytes
+const approxCidSizeBytes = 40
+
 // The datastore that was used to create the blockstore is a required parameter
 // used for calculating remaining disk space - the Blockstore interface itself
 // does not provide this information
@@ -82,6 +100,8 @@ func NewRandomPruner(
 
 	log.Infof("Initialized pruner's tracked size as %s", humanize.IBytes(size))
 
+	var cidMapApproxSize uint64 = cfg.Threshold * approxCidSizeBytes / approxBlockSizeBytes
+
 	pruner := &RandomPruner{
 		Blockstore:  inner,
 		datastore:   datastore,
@@ -89,8 +109,7 @@ func NewRandomPruner(
 		pruneBytes:  cfg.PruneBytes,
 		pinDuration: cfg.PinDuration,
 		size:        size,
-
-		pins: make(map[cid.Cid]time.Time),
+		allCids:     make(map[cid.Cid]*cidStatus, cidMapApproxSize),
 	}
 
 	// Poll immediately on startup and then periodically
@@ -115,6 +134,13 @@ func (pruner *RandomPruner) DeleteBlock(ctx context.Context, cid cid.Cid) error
 	}
 
 	pruner.size -= uint64(blockSize)
+	pruner.allCidsLk.Lock()
+	cs, ok := pruner.allCids[cid]
+	if ok {
+		delete(pruner.allCids, cid)
+		cidStatusPool.Put(cs)
+	}
+	pruner.allCidsLk.Unlock()
 
 	return nil
 }
@@ -190,12 +216,40 @@ func (pruner *RandomPruner) prune(ctx context.Context, bytesToPrune uint64) erro
 	log.Infof("Starting prune operation with original datastore size of %s", humanize.IBytes(pruner.size))
 	start := time.Now()
 
-	// Get all the keys in the blockstore
-	allCids, err := pruner.AllKeysChan(ctx)
-	if err != nil {
-		return err
+	// periodically sync the in memory list of all cids with disk
+	if time.Since(pruner.lastAllCidsUpdate) > time.Hour {
+		diskCids, err := pruner.AllKeysChan(ctx)
+		if err != nil {
+			return err
+		}
+		pruner.allCidsLk.Lock()
+		inMemoryCids := make(map[cid.Cid]struct{}, len(pruner.allCids))
+		for cid := range pruner.allCids {
+			inMemoryCids[cid] = struct{}{}
+		}
+		for diskCid := range diskCids {
+			if ctx.Err() != nil {
+				pruner.allCidsLk.Unlock()
+				return ctx.Err()
+			}
+			_, existing := pruner.allCids[diskCid]
+			if existing {
+				delete(inMemoryCids, diskCid)
+			} else {
+				cs := cidStatusPool.Get().(*cidStatus)
+				cs.pinned = false
+				pruner.allCids[diskCid] = cs
+			}
+		}
+		// delete remaining in memory cids that aren't on disk
+		for inMemoryCid := range inMemoryCids {
+			cs := pruner.allCids[inMemoryCid]
+			delete(pruner.allCids, inMemoryCid)
+			cidStatusPool.Put(cs)
+		}
+		pruner.allCidsLk.Unlock()
+		pruner.lastAllCidsUpdate = time.Now()
 	}
-
 	tmpFile, err := os.Create(path.Join(os.TempDir(), "autoretrieve-prune.txt"))
 	if err != nil {
 		return err
@@ -206,18 +260,21 @@ func (pruner *RandomPruner) prune(ctx context.Context, bytesToPrune uint64) erro
 	const cidPadLength = 64
 	writer := bufio.NewWriter(tmpFile)
 	cidCount := 0
-	for cid := range allCids {
-		if ctx.Err() != nil {
-			return ctx.Err()
-		}
 
-		// Don't consider pinned blocks for deletion
-		if pruner.isPinned(cid) {
+	pruner.allCidsLk.Lock()
+	for cid, status := range pruner.allCids {
+		if status.pinned && time.Since(status.pinTime) < pruner.pinDuration {
 			continue
 		}
 
+		status.pinned = false
+
 		paddedCidStr := fmt.Sprintf("%-*s", cidPadLength, cid.String())
+		if len(paddedCidStr) > cidPadLength {
+			paddedCidStr = paddedCidStr[:cidPadLength]
+		}
 		if _, err := writer.WriteString(paddedCidStr + "\n"); err != nil {
+			pruner.allCidsLk.Unlock()
 			return fmt.Errorf("failed to write cid to tmp file: %w", err)
 		}
 		cidCount++
@@ -295,25 +352,13 @@ func (pruner *RandomPruner) updatePin(pin cid.Cid) {
 	emptyPinClone := make([]byte, 0, len(pin.Bytes()))
 	pinClone := append(emptyPinClone, pin.Bytes()...)
 	pin = cid.MustParse(pinClone)
-	pruner.pinsLk.Lock()
-	pruner.pins[pin] = time.Now()
-	pruner.pinsLk.Unlock()
-}
-
-func (pruner *RandomPruner) isPinned(cid cid.Cid) bool {
-	pruner.pinsLk.Lock()
-	defer pruner.pinsLk.Unlock()
-
-	lastUse, ok := pruner.pins[cid]
+	pruner.allCidsLk.Lock()
+	cs, ok := pruner.allCids[pin]
 	if !ok {
-		return false
+		cs = cidStatusPool.Get().(*cidStatus)
+		pruner.allCids[pin] = cs
 	}
-
-	if time.Since(lastUse) < pruner.pinDuration {
-		return true
-	}
-
-	delete(pruner.pins, cid)
-	return false
-
+	cs.pinned = true
+	cs.pinTime = time.Now()
+	pruner.allCidsLk.Unlock()
 }