diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2ba20e167f9e..45edecfdfe6b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -54,6 +54,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * [#261](https://github.com/crypto-org-chain/cosmos-sdk/pull/261) `ctx.BlockHeader` don't do protobuf deep copy, shallow copy seems enough, reduce scope of mutex in `PriorityNonceMempool.Remove`.
 * [#507](https://github.com/crypto-org-chain/cosmos-sdk/pull/507) mempool respect gas wanted returned by ante handler
 * [#744](https://github.com/crypto-org-chain/cosmos-sdk/pull/744) Pass raw transactions to tx executor so it can do pre-estimations.
+* [#884](https://github.com/crypto-org-chain/cosmos-sdk/pull/884) Avoid decoding tx for in PrepareProposal if it's NopMempool.
 
 ## [Unreleased]
 
diff --git a/baseapp/abci_utils.go b/baseapp/abci_utils.go
index 1bbd500bd705..dc532c191b0c 100644
--- a/baseapp/abci_utils.go
+++ b/baseapp/abci_utils.go
@@ -212,6 +212,9 @@ type (
 		txVerifier       ProposalTxVerifier
 		txSelector       TxSelector
 		signerExtAdapter mempool.SignerExtractionAdapter
+
+		// fastPrepareProposal together with NoOpMempool will bypass tx selector
+		fastPrepareProposal bool
 	}
 )
 
@@ -224,6 +227,12 @@ func NewDefaultProposalHandler(mp mempool.Mempool, txVerifier ProposalTxVerifier
 	}
 }
 
+func NewDefaultProposalHandlerFast(mp mempool.Mempool, txVerifier ProposalTxVerifier) *DefaultProposalHandler {
+	h := NewDefaultProposalHandler(mp, txVerifier)
+	h.fastPrepareProposal = true
+	return h
+}
+
 // SetTxSelector sets the TxSelector function on the DefaultProposalHandler.
 func (h *DefaultProposalHandler) SetTxSelector(ts TxSelector) {
 	h.txSelector = ts
@@ -264,6 +273,11 @@ func (h *DefaultProposalHandler) PrepareProposalHandler() sdk.PrepareProposalHan
 		// Note, we still need to ensure the transactions returned respect req.MaxTxBytes.
 		_, isNoOp := h.mempool.(mempool.NoOpMempool)
 		if h.mempool == nil || isNoOp {
+			if h.fastPrepareProposal {
+				txs := h.txSelector.SelectTxForProposalFast(ctx, req.Txs)
+				return &abci.ResponsePrepareProposal{Txs: txs}, nil
+			}
+
 			for _, txBz := range req.Txs {
 				tx, err := h.txVerifier.TxDecode(txBz)
 				if err != nil {
@@ -464,6 +478,12 @@ type TxSelector interface {
 	// return <true> if the caller should halt the transaction selection loop
 	// (typically over a mempool) or <false> otherwise.
 	SelectTxForProposal(ctx context.Context, maxTxBytes, maxBlockGas uint64, memTx sdk.Tx, txBz []byte, gasWanted uint64) bool
+
+	// SelectTxForProposalFast is called in the case of NoOpMempool,
+	// where cometbft already checked the block gas/size limit,
+	// so the tx selector should simply accept them all to the proposal.
+	// But extra validations on the tx are still possible though.
+	SelectTxForProposalFast(ctx context.Context, txs [][]byte) [][]byte
 }
 
 type defaultTxSelector struct {
@@ -485,7 +505,7 @@ func (ts *defaultTxSelector) SelectedTxs(_ context.Context) [][]byte {
 func (ts *defaultTxSelector) Clear() {
 	ts.totalTxBytes = 0
 	ts.totalTxGas = 0
-	ts.selectedTxs = nil
+	ts.selectedTxs = ts.selectedTxs[:0] // keep the allocated memory
 }
 
 func (ts *defaultTxSelector) SelectTxForProposal(_ context.Context, maxTxBytes, maxBlockGas uint64, memTx sdk.Tx, txBz []byte, gasWanted uint64) bool {
@@ -510,3 +530,7 @@ func (ts *defaultTxSelector) SelectTxForProposal(_ context.Context, maxTxBytes,
 	// check if we've reached capacity; if so, we cannot select any more transactions
 	return ts.totalTxBytes >= maxTxBytes || (maxBlockGas > 0 && (ts.totalTxGas >= maxBlockGas))
 }
+
+func (ts *defaultTxSelector) SelectTxForProposalFast(ctx context.Context, txs [][]byte) [][]byte {
+	return txs
+}