diff --git a/beacon-chain/blockchain/process_block.go b/beacon-chain/blockchain/process_block.go
index a034aca26..5a4238f30 100644
--- a/beacon-chain/blockchain/process_block.go
+++ b/beacon-chain/blockchain/process_block.go
@@ -103,30 +103,6 @@ func (s *Service) postBlockProcess(ctx context.Context, signed interfaces.ReadOn
 			proposingSlot: proposingSlot,
 		}
 	} else {
-		// Updating next slot state cache can happen in the background
-		// except in the epoch boundary in which case we lock to handle
-		// the shuffling and proposer caches updates.
-		// We handle these caches only on canonical
-		// blocks, otherwise this will be handled by lateBlockTasks
-		slot := postState.Slot()
-		if slots.IsEpochEnd(slot) {
-			if err := transition.UpdateNextSlotCache(ctx, blockRoot[:], postState); err != nil {
-				return errors.Wrap(err, "could not update next slot state cache")
-			}
-			if err := s.handleEpochBoundary(ctx, slot, postState, blockRoot[:]); err != nil {
-				return errors.Wrap(err, "could not handle epoch boundary")
-			}
-		} else {
-			go func() {
-				slotCtx, cancel := context.WithTimeout(context.Background(), slotDeadline)
-				defer cancel()
-				if err := transition.UpdateNextSlotCache(slotCtx, blockRoot[:], postState); err != nil {
-					log.WithError(err).Error("could not update next slot state cache")
-				}
-			}()
-		}
-		// verify conditions for FCU, notifies FCU, and saves the new head.
-		// This function also prunes attestations, other similar operations happen in prunePostBlockOperationPools.
 		fcuArgs = &fcuConfig{
 			headState:     postState,
 			headBlock:     signed,
@@ -134,17 +110,37 @@ func (s *Service) postBlockProcess(ctx context.Context, signed interfaces.ReadOn
 			proposingSlot: proposingSlot,
 		}
 	}
+	isEarly := slots.WithinVotingWindow(uint64(s.genesisTime.Unix()))
+	shouldOverrideFCU := false
+	slot := postState.Slot()
 	if s.isNewHead(headRoot) {
-		shouldOverrideFCU := false
-		_, tracked := s.trackedProposer(fcuArgs.headState, proposingSlot)
-		if tracked {
-			shouldOverrideFCU = s.shouldOverrideFCU(headRoot, proposingSlot)
-			fcuArgs.attributes = s.getPayloadAttribute(ctx, fcuArgs.headState, proposingSlot, headRoot[:])
-		}
-		if !shouldOverrideFCU {
+		// if the block is early send FCU without any payload attributes
+		if isEarly {
 			if err := s.forkchoiceUpdateWithExecution(ctx, fcuArgs); err != nil {
 				return err
 			}
+		} else {
+			// if the block is late lock and update the caches
+			if blockRoot == headRoot {
+				if err := transition.UpdateNextSlotCache(ctx, blockRoot[:], postState); err != nil {
+					return errors.Wrap(err, "could not update next slot state cache")
+				}
+				if slots.IsEpochEnd(slot) {
+					if err := s.handleEpochBoundary(ctx, slot, postState, blockRoot[:]); err != nil {
+						return errors.Wrap(err, "could not handle epoch boundary")
+					}
+				}
+			}
+			_, tracked := s.trackedProposer(fcuArgs.headState, proposingSlot)
+			if tracked {
+				shouldOverrideFCU = s.shouldOverrideFCU(headRoot, proposingSlot)
+				fcuArgs.attributes = s.getPayloadAttribute(ctx, fcuArgs.headState, proposingSlot, headRoot[:])
+			}
+			if !shouldOverrideFCU {
+				if err := s.forkchoiceUpdateWithExecution(ctx, fcuArgs); err != nil {
+					return err
+				}
+			}
 		}
 	}
 	optimistic, err := s.cfg.ForkChoiceStore.IsOptimistic(blockRoot)
@@ -163,7 +159,29 @@ func (s *Service) postBlockProcess(ctx context.Context, signed interfaces.ReadOn
 			Optimistic:  optimistic,
 		},
 	})
-
+	if blockRoot == headRoot && isEarly {
+		go func() {
+			slotCtx, cancel := context.WithTimeout(context.Background(), slotDeadline)
+			defer cancel()
+			if err := transition.UpdateNextSlotCache(slotCtx, blockRoot[:], postState); err != nil {
+				log.WithError(err).Error("could not update next slot state cache")
+			}
+			if slots.IsEpochEnd(slot) {
+				if err := s.handleEpochBoundary(ctx, slot, postState, blockRoot[:]); err != nil {
+					log.WithError(err).Error("could not handle epoch boundary")
+				}
+			}
+			if _, tracked := s.trackedProposer(fcuArgs.headState, proposingSlot); !tracked {
+				return
+			}
+			fcuArgs.attributes = s.getPayloadAttribute(ctx, fcuArgs.headState, proposingSlot, headRoot[:])
+			s.cfg.ForkChoiceStore.RLock()
+			defer s.cfg.ForkChoiceStore.RUnlock()
+			if _, err := s.notifyForkchoiceUpdate(ctx, fcuArgs); err != nil {
+				log.WithError(err).Error("could not update forkchoice with payload attributes for proposal")
+			}
+		}()
+	}
 	defer reportAttestationInclusion(b)
 	onBlockProcessingTime.Observe(float64(time.Since(startTime).Milliseconds()))
 	return nil
diff --git a/beacon-chain/blockchain/process_block_test.go b/beacon-chain/blockchain/process_block_test.go
index f313d5010..fc53ce923 100644
--- a/beacon-chain/blockchain/process_block_test.go
+++ b/beacon-chain/blockchain/process_block_test.go
@@ -2045,7 +2045,7 @@ func TestFillMissingBlockPayloadId_PrepareAllPayloads(t *testing.T) {
 // Helper function to simulate the block being on time or delayed for proposer
 // boost. It alters the genesisTime tracked by the store.
 func driftGenesisTime(s *Service, slot, delay int64) {
-	offset := slot*int64(params.BeaconConfig().SecondsPerSlot) - delay
+	offset := slot*int64(params.BeaconConfig().SecondsPerSlot) + delay
 	s.SetGenesisTime(time.Unix(time.Now().Unix()-offset, 0))
 }
 
diff --git a/beacon-chain/core/helpers/validators.go b/beacon-chain/core/helpers/validators.go
index c34d884a6..2fea24d71 100644
--- a/beacon-chain/core/helpers/validators.go
+++ b/beacon-chain/core/helpers/validators.go
@@ -302,7 +302,7 @@ func BeaconProposerIndexAtSlot(ctx context.Context, state state.ReadOnlyBeaconSt
 				return pid, nil
 			}
 			if err := UpdateProposerIndicesInCache(ctx, state, e); err != nil {
-				return 0, errors.Wrap(err, "could not update committee cache")
+				return 0, errors.Wrap(err, "could not update proposer index cache")
 			}
 			pid, err = cachedProposerIndexAtSlot(slot, [32]byte(r))
 			if err == nil {
diff --git a/time/slots/slottime.go b/time/slots/slottime.go
index 61bea59c7..1e2f5cf28 100644
--- a/time/slots/slottime.go
+++ b/time/slots/slottime.go
@@ -16,9 +16,6 @@ import (
 // incoming objects. (24 mins with mainnet spec)
 const MaxSlotBuffer = uint64(1 << 7)
 
-// votingWindow specifies the deadline for attestations
-var votingWindow = params.BeaconConfig().SecondsPerSlot / params.BeaconConfig().IntervalsPerSlot
-
 // startFromTime returns the slot start in terms of genesis time.Time
 func startFromTime(genesis time.Time, slot primitives.Slot) time.Time {
 	duration := time.Second * time.Duration(slot.Mul(params.BeaconConfig().SecondsPerSlot))
@@ -271,5 +268,6 @@ func TimeIntoSlot(genesisTime uint64) time.Duration {
 // WithinVotingWindow returns whether the current time is within the voting window
 // (eg. 4 seconds on mainnet) of the current slot.
 func WithinVotingWindow(genesisTime uint64) bool {
+	votingWindow := params.BeaconConfig().SecondsPerSlot / params.BeaconConfig().IntervalsPerSlot
 	return TimeIntoSlot(genesisTime) < time.Duration(votingWindow)*time.Second
 }