diff --git a/.changeset/reduced_host_sector_hashing_in_rpcwritesector.md b/.changeset/reduced_host_sector_hashing_in_rpcwritesector.md
new file mode 100644
index 00000000..3f22d6a8
--- /dev/null
+++ b/.changeset/reduced_host_sector_hashing_in_rpcwritesector.md
@@ -0,0 +1,5 @@
+---
+default: patch
+---
+
+# Reduced host sector hashing in RPCWriteSector.
\ No newline at end of file
diff --git a/rhp/v4/rpc_test.go b/rhp/v4/rpc_test.go
index 01efae36..4b8a2dcf 100644
--- a/rhp/v4/rpc_test.go
+++ b/rhp/v4/rpc_test.go
@@ -1706,14 +1706,16 @@ func TestAccounts(t *testing.T) {
 
 	cs := cm.TipState()
 
-	var sector *[proto4.SectorSize]byte
-	if err := ss.StoreSector(types.Hash256{1}, sector, 0); err != nil {
+	sector := [proto4.SectorSize]byte{1}
+	subtrees := proto4.CachedSectorSubtrees(&sector)
+	root := proto4.MetaRoot(subtrees)
+	if err := ss.StoreSector(root, &sector, subtrees, 0); err != nil {
 		t.Fatal(err)
 	}
 
 	// test operations against unknown account
 	token := proto4.NewAccountToken(renterKey, hostKey.PublicKey())
-	_, err = rhp4.RPCVerifySector(context.Background(), transport, settings.Prices, token, types.Hash256{1})
+	_, err = rhp4.RPCVerifySector(context.Background(), transport, settings.Prices, token, root)
 	if err == nil || !strings.Contains(err.Error(), proto4.ErrNotEnoughFunds.Error()) {
 		t.Fatal(err)
 	}
@@ -1772,7 +1774,7 @@ func TestAccounts(t *testing.T) {
 
 	// drain account and try using it
 	_ = c.DebitAccount(account, proto4.Usage{RPC: accountFundAmount})
-	_, err = rhp4.RPCVerifySector(context.Background(), transport, settings.Prices, token, types.Hash256{1})
+	_, err = rhp4.RPCVerifySector(context.Background(), transport, settings.Prices, token, root)
 	if err == nil || !strings.Contains(err.Error(), proto4.ErrNotEnoughFunds.Error()) {
 		t.Fatal(err)
 	}
diff --git a/rhp/v4/server.go b/rhp/v4/server.go
index bd06bbc3..1dde0944 100644
--- a/rhp/v4/server.go
+++ b/rhp/v4/server.go
@@ -81,8 +81,8 @@ type (
 		HasSector(root types.Hash256) (bool, error)
 		// ReadSector retrieves a segment of a sector by its root and returns the data and a proof for the segment.
 		ReadSector(root types.Hash256, offset, length uint64) ([]byte, []types.Hash256, error)
-		// StoreSector writes a sector to disk
-		StoreSector(root types.Hash256, data *[rhp4.SectorSize]byte, expiration uint64) error
+		// StoreSector writes a sector to disk.
+		StoreSector(root types.Hash256, data *[rhp4.SectorSize]byte, subtrees []types.Hash256, expiration uint64) error
 	}
 
 	// A RevisionState pairs a contract revision with its sector roots.
@@ -240,26 +240,21 @@ func (s *Server) handleRPCWriteSector(stream net.Conn) error {
 	}
 	prices := req.Prices
 
-	sr := io.LimitReader(stream, int64(req.DataLength))
-	if req.DataLength < rhp4.SectorSize {
-		// if the data is less than a full sector, the reader needs to be padded
-		// with zeros to calculate the sector root
-		padding := int64(rhp4.SectorSize - req.DataLength)
-		sr = io.MultiReader(sr, io.LimitReader(zeros, padding))
-	}
-
 	buf := newSectorBuffer()
-	root, err := rhp4.ReadSectorRoot(io.TeeReader(sr, buf))
-	if err != nil {
+	if _, err := io.CopyN(buf, stream, int64(req.DataLength)); err != nil {
 		return errorDecodingError("failed to read sector data: %v", err)
 	}
 
 	usage := prices.RPCWriteSectorCost(req.DataLength)
-	if err = s.contractor.DebitAccount(req.Token.Account, usage); err != nil {
+	if err := s.contractor.DebitAccount(req.Token.Account, usage); err != nil {
 		return fmt.Errorf("failed to debit account: %w", err)
 	}
 
-	if err := s.sectors.StoreSector(root, buf.Bytes(), prices.TipHeight+rhp4.TempSectorDuration); err != nil {
+	subtrees := rhp4.CachedSectorSubtrees(buf.Bytes())
+	// compute the root from the subtrees instead of hashing the sector again.
+	root := rhp4.MetaRoot(subtrees)
+
+	if err := s.sectors.StoreSector(root, buf.Bytes(), subtrees, prices.TipHeight+rhp4.TempSectorDuration); err != nil {
 		return fmt.Errorf("failed to store sector: %w", err)
 	}
 	return rhp4.WriteResponse(stream, &rhp4.RPCWriteSectorResponse{
diff --git a/testutil/host.go b/testutil/host.go
index 95d4a5ba..06fb968b 100644
--- a/testutil/host.go
+++ b/testutil/host.go
@@ -72,7 +72,7 @@ func (es *EphemeralSectorStore) ReadSector(root types.Hash256, offset, length ui
 }
 
 // StoreSector stores a sector in the EphemeralSectorStore.
-func (es *EphemeralSectorStore) StoreSector(root types.Hash256, sector *[proto4.SectorSize]byte, _ uint64) error {
+func (es *EphemeralSectorStore) StoreSector(root types.Hash256, sector *[proto4.SectorSize]byte, _ []types.Hash256, _ uint64) error {
 	es.mu.Lock()
 	defer es.mu.Unlock()
 	es.sectors[root] = sector