diff --git a/tortoise/state.go b/tortoise/state.go
index 362c648b78..1be4141b1f 100644
--- a/tortoise/state.go
+++ b/tortoise/state.go
@@ -94,7 +94,7 @@ func (s *state) layer(lid types.LayerID) *layerInfo {
 	layer, exist := s.layers[lid]
 	if !exist {
 		layersNumber.Inc()
-		layer = &layerInfo{lid: lid}
+		layer = &layerInfo{lid: lid, opinions: map[types.Hash32]votes{}}
 		s.layers[lid] = layer
 	}
 	return layer
@@ -179,6 +179,10 @@ type layerInfo struct {
 	verifying      verifyingInfo
 	coinflip       sign
 
+	// unique opinions recorded from the ballots in this layer.
+	// ballot votes an opinion and encodes sidecar
+	opinions map[types.Hash32]votes
+
 	opinion types.Hash32
 	// a pointer to the value stored on the previous layerInfo object
 	// it is stored as a pointer so that when previous layerInfo is evicted
diff --git a/tortoise/tortoise.go b/tortoise/tortoise.go
index 0142fd8477..b6a8f54531 100644
--- a/tortoise/tortoise.go
+++ b/tortoise/tortoise.go
@@ -60,6 +60,7 @@ func newTurtle(logger *zap.Logger, config Config) *turtle {
 	t.layers[genesis] = &layerInfo{
 		lid:            genesis,
 		hareTerminated: true,
+		opinions:       map[types.Hash32]votes{},
 	}
 	t.verifying = newVerifying(config, t.state)
 	t.full = newFullTortoise(config, t.state)
@@ -748,11 +749,23 @@ func (t *turtle) decodeBallot(ballot *types.BallotTortoiseData) (*ballotInfo, ty
 		zap.Uint32("lid", ballot.Layer.Uint32()),
 	)
 
-	votes, min, err := decodeVotes(t.evicted, binfo.layer, base, ballot.Opinion.Votes)
-	if err != nil {
-		return nil, 0, err
+	layer := t.layer(binfo.layer)
+
+	existing, exists := layer.opinions[ballot.Opinion.Hash]
+	var min types.LayerID
+	if exists {
+		binfo.votes = existing
+	} else {
+		var (
+			votes votes
+			err   error
+		)
+		votes, min, err = decodeVotes(t.evicted, binfo.layer, base, ballot.Opinion.Votes)
+		if err != nil {
+			return nil, 0, err
+		}
+		binfo.votes = votes
 	}
-	binfo.votes = votes
 	t.logger.Debug("decoded exceptions",
 		zap.Stringer("block", binfo.id),
 		zap.Uint32("lid", binfo.layer.Uint32()),
@@ -771,15 +784,22 @@ func (t *turtle) storeBallot(ballot *ballotInfo, min types.LayerID) error {
 	}
 
 	t.state.addBallot(ballot)
-	for current := ballot.votes.tail; current != nil && !current.lid.Before(min); current = current.prev {
-		for i, block := range current.supported {
-			existing := t.getBlock(block.header())
-			if existing != nil {
-				current.supported[i] = existing
-			} else {
-				t.addBlock(block)
+	layer := t.layer(ballot.layer)
+	existing, exists := layer.opinions[ballot.opinion()]
+	if exists {
+		ballot.votes = existing
+	} else {
+		for current := ballot.votes.tail; current != nil && !current.lid.Before(min); current = current.prev {
+			for i, block := range current.supported {
+				existing := t.getBlock(block.header())
+				if existing != nil {
+					current.supported[i] = existing
+				} else {
+					t.addBlock(block)
+				}
 			}
 		}
+		layer.opinions[ballot.opinion()] = ballot.votes
 	}
 	if !ballot.layer.After(t.processed) {
 		if err := t.countBallot(ballot); err != nil {