diff --git a/beacon-chain/blockchain/chain_info.go b/beacon-chain/blockchain/chain_info.go
index be4682b82082..c7dbf96c2490 100644
--- a/beacon-chain/blockchain/chain_info.go
+++ b/beacon-chain/blockchain/chain_info.go
@@ -556,3 +556,18 @@ func (s *Service) RecentBlockSlot(root [32]byte) (primitives.Slot, error) {
 	defer s.cfg.ForkChoiceStore.RUnlock()
 	return s.cfg.ForkChoiceStore.Slot(root)
 }
+
+// inRegularSync applies the following heuristics to decide if the node is in
+// regular sync mode vs init sync mode using only forkchoice.
+// It checks that the highest received block is behind the current time by at least 2 epochs
+// and that it was imported at least one epoch late if both of these
+// tests pass then the node is in init sync. The caller of this function MUST
+// have a lock on forkchoice
+func (s *Service) inRegularSync() bool {
+	currentSlot := s.CurrentSlot()
+	fc := s.cfg.ForkChoiceStore
+	if currentSlot-fc.HighestReceivedBlockSlot() < 2*params.BeaconConfig().SlotsPerEpoch {
+		return true
+	}
+	return fc.HighestReceivedBlockDelay() < params.BeaconConfig().SlotsPerEpoch
+}
diff --git a/beacon-chain/blockchain/chain_info_test.go b/beacon-chain/blockchain/chain_info_test.go
index 044eb89c8f36..5d1187e73d2d 100644
--- a/beacon-chain/blockchain/chain_info_test.go
+++ b/beacon-chain/blockchain/chain_info_test.go
@@ -593,3 +593,26 @@ func TestService_IsFinalized(t *testing.T) {
 	require.Equal(t, true, c.IsFinalized(ctx, br))
 	require.Equal(t, false, c.IsFinalized(ctx, [32]byte{'c'}))
 }
+
+func TestService_inRegularSync(t *testing.T) {
+	ctx := context.Background()
+	c := &Service{cfg: &config{ForkChoiceStore: doublylinkedtree.New()}, head: &head{root: [32]byte{'b'}}}
+	ojc := &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
+	ofc := &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
+	st, blkRoot, err := prepareForkchoiceState(ctx, 100, [32]byte{'a'}, [32]byte{}, params.BeaconConfig().ZeroHash, ojc, ofc)
+	require.NoError(t, err)
+	require.NoError(t, c.cfg.ForkChoiceStore.InsertNode(ctx, st, blkRoot))
+	require.Equal(t, false, c.inRegularSync())
+	c.SetGenesisTime(time.Now().Add(time.Second * time.Duration(-1*int64(params.BeaconConfig().SlotsPerEpoch)*int64(params.BeaconConfig().SecondsPerSlot))))
+	st, blkRoot, err = prepareForkchoiceState(ctx, 128, [32]byte{'b'}, [32]byte{'a'}, params.BeaconConfig().ZeroHash, ojc, ofc)
+	require.NoError(t, err)
+	require.NoError(t, c.cfg.ForkChoiceStore.InsertNode(ctx, st, blkRoot))
+	require.Equal(t, false, c.inRegularSync())
+
+	c.SetGenesisTime(time.Now().Add(time.Second * time.Duration(-5*int64(params.BeaconConfig().SlotsPerEpoch)*int64(params.BeaconConfig().SecondsPerSlot))))
+	require.Equal(t, true, c.inRegularSync())
+
+	c.SetGenesisTime(time.Now().Add(time.Second * time.Duration(-1*int64(params.BeaconConfig().SlotsPerEpoch)*int64(params.BeaconConfig().SecondsPerSlot))))
+	c.cfg.ForkChoiceStore.SetGenesisTime(uint64(time.Now().Unix()))
+	require.Equal(t, true, c.inRegularSync())
+}
diff --git a/beacon-chain/blockchain/process_block.go b/beacon-chain/blockchain/process_block.go
index 824f213f77e2..ad68205d665e 100644
--- a/beacon-chain/blockchain/process_block.go
+++ b/beacon-chain/blockchain/process_block.go
@@ -67,7 +67,9 @@ func (s *Service) postBlockProcess(cfg *postBlockProcessConfig) error {
 	startTime := time.Now()
 	fcuArgs := &fcuConfig{}
 
-	defer s.handleSecondFCUCall(cfg, fcuArgs)
+	if s.inRegularSync() {
+		defer s.handleSecondFCUCall(cfg, fcuArgs)
+	}
 	defer s.sendLightClientFeeds(cfg)
 	defer s.sendStateFeedOnBlock(cfg)
 	defer reportProcessingTime(startTime)
@@ -580,10 +582,15 @@ func (s *Service) lateBlockTasks(ctx context.Context) {
 	if s.CurrentSlot() == s.HeadSlot() {
 		return
 	}
+	s.cfg.ForkChoiceStore.RLock()
+	defer s.cfg.ForkChoiceStore.RUnlock()
+	// return early if we are in init sync
+	if !s.inRegularSync() {
+		return
+	}
 	s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
 		Type: statefeed.MissedSlot,
 	})
-
 	s.headLock.RLock()
 	headRoot := s.headRoot()
 	headState := s.headState(ctx)
@@ -598,12 +605,9 @@ func (s *Service) lateBlockTasks(ctx context.Context) {
 	if err := transition.UpdateNextSlotCache(ctx, lastRoot, lastState); err != nil {
 		log.WithError(err).Debug("could not update next slot state cache")
 	}
-	// handleEpochBoundary requires a forkchoice lock to obtain the target root.
-	s.cfg.ForkChoiceStore.RLock()
 	if err := s.handleEpochBoundary(ctx, currentSlot, headState, headRoot[:]); err != nil {
 		log.WithError(err).Error("lateBlockTasks: could not update epoch boundary caches")
 	}
-	s.cfg.ForkChoiceStore.RUnlock()
 	// return early if we already started building a block for the current
 	// head root
 	_, has := s.cfg.PayloadIDCache.PayloadID(s.CurrentSlot()+1, headRoot)
@@ -629,9 +633,7 @@ func (s *Service) lateBlockTasks(ctx context.Context) {
 	if fcuArgs.attributes.IsEmpty() {
 		return
 	}
-	s.cfg.ForkChoiceStore.RLock()
 	_, err = s.notifyForkchoiceUpdate(ctx, fcuArgs)
-	s.cfg.ForkChoiceStore.RUnlock()
 	if err != nil {
 		log.WithError(err).Debug("could not perform late block tasks: failed to update forkchoice with engine")
 	}
diff --git a/beacon-chain/blockchain/process_block_helpers.go b/beacon-chain/blockchain/process_block_helpers.go
index bfbc407da86f..db84896b65f7 100644
--- a/beacon-chain/blockchain/process_block_helpers.go
+++ b/beacon-chain/blockchain/process_block_helpers.go
@@ -37,6 +37,9 @@ func (s *Service) getFCUArgs(cfg *postBlockProcessConfig, fcuArgs *fcuConfig) er
 	if err := s.getFCUArgsEarlyBlock(cfg, fcuArgs); err != nil {
 		return err
 	}
+	if !s.inRegularSync() {
+		return nil
+	}
 	slot := cfg.signed.Block().Slot()
 	if slots.WithinVotingWindow(uint64(s.genesisTime.Unix()), slot) {
 		return nil
diff --git a/beacon-chain/blockchain/receive_attestation.go b/beacon-chain/blockchain/receive_attestation.go
index bdfd666ca0ef..db5c5de9c476 100644
--- a/beacon-chain/blockchain/receive_attestation.go
+++ b/beacon-chain/blockchain/receive_attestation.go
@@ -150,7 +150,9 @@ func (s *Service) UpdateHead(ctx context.Context, proposingSlot primitives.Slot)
 		headBlock:     headBlock,
 		proposingSlot: proposingSlot,
 	}
-	fcuArgs.attributes = s.getPayloadAttribute(ctx, headState, proposingSlot, newHeadRoot[:])
+	if s.inRegularSync() {
+		fcuArgs.attributes = s.getPayloadAttribute(ctx, headState, proposingSlot, newHeadRoot[:])
+	}
 	if fcuArgs.attributes != nil && s.shouldOverrideFCU(newHeadRoot, proposingSlot) {
 		return
 	}
diff --git a/beacon-chain/forkchoice/doubly-linked-tree/store.go b/beacon-chain/forkchoice/doubly-linked-tree/store.go
index 79eb00f9ae0d..da98f1b8cbaf 100644
--- a/beacon-chain/forkchoice/doubly-linked-tree/store.go
+++ b/beacon-chain/forkchoice/doubly-linked-tree/store.go
@@ -240,6 +240,20 @@ func (f *ForkChoice) HighestReceivedBlockSlot() primitives.Slot {
 	return f.store.highestReceivedNode.slot
 }
 
+// HighestReceivedBlockSlotDelay returns the number of slots that the highest
+// received block was late when receiving it
+func (f *ForkChoice) HighestReceivedBlockDelay() primitives.Slot {
+	n := f.store.highestReceivedNode
+	if n == nil {
+		return 0
+	}
+	secs, err := slots.SecondsSinceSlotStart(n.slot, f.store.genesisTime, n.timestamp)
+	if err != nil {
+		return 0
+	}
+	return primitives.Slot(secs / params.BeaconConfig().SecondsPerSlot)
+}
+
 // ReceivedBlocksLastEpoch returns the number of blocks received in the last epoch
 func (f *ForkChoice) ReceivedBlocksLastEpoch() (uint64, error) {
 	count := uint64(0)
diff --git a/beacon-chain/forkchoice/doubly-linked-tree/store_test.go b/beacon-chain/forkchoice/doubly-linked-tree/store_test.go
index b38d3686c4a3..580154a318a7 100644
--- a/beacon-chain/forkchoice/doubly-linked-tree/store_test.go
+++ b/beacon-chain/forkchoice/doubly-linked-tree/store_test.go
@@ -333,26 +333,29 @@ func TestForkChoice_ReceivedBlocksLastEpoch(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, uint64(1), count)
 	require.Equal(t, primitives.Slot(1), f.HighestReceivedBlockSlot())
+	require.Equal(t, primitives.Slot(0), f.HighestReceivedBlockDelay())
 
 	// 64
 	// Received block last epoch is 1
 	_, err = s.insert(context.Background(), 64, [32]byte{'A'}, b, b, 1, 1)
 	require.NoError(t, err)
-	s.genesisTime = uint64(time.Now().Add(time.Duration(-64*int64(params.BeaconConfig().SecondsPerSlot)) * time.Second).Unix())
+	s.genesisTime = uint64(time.Now().Add(time.Duration((-64*int64(params.BeaconConfig().SecondsPerSlot))-1) * time.Second).Unix())
 	count, err = f.ReceivedBlocksLastEpoch()
 	require.NoError(t, err)
 	require.Equal(t, uint64(1), count)
 	require.Equal(t, primitives.Slot(64), f.HighestReceivedBlockSlot())
+	require.Equal(t, primitives.Slot(0), f.HighestReceivedBlockDelay())
 
 	// 64 65
 	// Received block last epoch is 2
 	_, err = s.insert(context.Background(), 65, [32]byte{'B'}, b, b, 1, 1)
 	require.NoError(t, err)
-	s.genesisTime = uint64(time.Now().Add(time.Duration(-65*int64(params.BeaconConfig().SecondsPerSlot)) * time.Second).Unix())
+	s.genesisTime = uint64(time.Now().Add(time.Duration(-66*int64(params.BeaconConfig().SecondsPerSlot)) * time.Second).Unix())
 	count, err = f.ReceivedBlocksLastEpoch()
 	require.NoError(t, err)
 	require.Equal(t, uint64(2), count)
 	require.Equal(t, primitives.Slot(65), f.HighestReceivedBlockSlot())
+	require.Equal(t, primitives.Slot(1), f.HighestReceivedBlockDelay())
 
 	// 64 65 66
 	// Received block last epoch is 3
diff --git a/beacon-chain/forkchoice/interfaces.go b/beacon-chain/forkchoice/interfaces.go
index 8ce0a80504cf..dd4bb65c5701 100644
--- a/beacon-chain/forkchoice/interfaces.go
+++ b/beacon-chain/forkchoice/interfaces.go
@@ -64,6 +64,7 @@ type FastGetter interface {
 	FinalizedPayloadBlockHash() [32]byte
 	HasNode([32]byte) bool
 	HighestReceivedBlockSlot() primitives.Slot
+	HighestReceivedBlockDelay() primitives.Slot
 	IsCanonical(root [32]byte) bool
 	IsOptimistic(root [32]byte) (bool, error)
 	IsViableForCheckpoint(*forkchoicetypes.Checkpoint) (bool, error)
diff --git a/beacon-chain/forkchoice/ro.go b/beacon-chain/forkchoice/ro.go
index 995bcd33e946..6d9caddd2fc0 100644
--- a/beacon-chain/forkchoice/ro.go
+++ b/beacon-chain/forkchoice/ro.go
@@ -114,6 +114,13 @@ func (ro *ROForkChoice) HighestReceivedBlockSlot() primitives.Slot {
 	return ro.getter.HighestReceivedBlockSlot()
 }
 
+// HighestReceivedBlockDelay delegates to the underlying forkchoice call, under a lock.
+func (ro *ROForkChoice) HighestReceivedBlockDelay() primitives.Slot {
+	ro.l.RLock()
+	defer ro.l.RUnlock()
+	return ro.getter.HighestReceivedBlockDelay()
+}
+
 // ReceivedBlocksLastEpoch delegates to the underlying forkchoice call, under a lock.
 func (ro *ROForkChoice) ReceivedBlocksLastEpoch() (uint64, error) {
 	ro.l.RLock()
diff --git a/beacon-chain/forkchoice/ro_test.go b/beacon-chain/forkchoice/ro_test.go
index 5cbbb34ef4ca..8bf94071e222 100644
--- a/beacon-chain/forkchoice/ro_test.go
+++ b/beacon-chain/forkchoice/ro_test.go
@@ -29,6 +29,7 @@ const (
 	unrealizedJustifiedPayloadBlockHashCalled
 	nodeCountCalled
 	highestReceivedBlockSlotCalled
+	highestReceivedBlockDelayCalled
 	receivedBlocksLastEpochCalled
 	weightCalled
 	isOptimisticCalled
@@ -113,6 +114,11 @@ func TestROLocking(t *testing.T) {
 			call: highestReceivedBlockSlotCalled,
 			cb:   func(g FastGetter) { g.HighestReceivedBlockSlot() },
 		},
+		{
+			name: "highestReceivedBlockDelayCalled",
+			call: highestReceivedBlockDelayCalled,
+			cb:   func(g FastGetter) { g.HighestReceivedBlockDelay() },
+		},
 		{
 			name: "receivedBlocksLastEpochCalled",
 			call: receivedBlocksLastEpochCalled,
@@ -245,6 +251,11 @@ func (ro *mockROForkchoice) HighestReceivedBlockSlot() primitives.Slot {
 	return 0
 }
 
+func (ro *mockROForkchoice) HighestReceivedBlockDelay() primitives.Slot {
+	ro.calls = append(ro.calls, highestReceivedBlockDelayCalled)
+	return 0
+}
+
 func (ro *mockROForkchoice) ReceivedBlocksLastEpoch() (uint64, error) {
 	ro.calls = append(ro.calls, receivedBlocksLastEpochCalled)
 	return 0, nil