Problem: subUnlockedCoins is not optimal

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.
+* [#]() Optimize subUnlockedCoins implementation.
 
 ## [Unreleased]
 

x/bank/keeper/send.go

@@ -8,7 +8,7 @@ import (
 	"cosmossdk.io/core/store"
 	errorsmod "cosmossdk.io/errors"
 	"cosmossdk.io/log"
-	"cosmossdk.io/math"
+	sdkmath "cosmossdk.io/math"
 	storetypes "cosmossdk.io/store/types"
 
 	"github.com/cosmos/cosmos-sdk/codec"
@@ -274,28 +274,20 @@ func (k BaseSendKeeper) subUnlockedCoins(ctx context.Context, addr sdk.AccAddres
 	lockedCoins := k.LockedCoins(ctx, addr)
 
 	for _, coin := range amt {
-		balance := k.GetBalance(ctx, addr, coin.Denom)
-		locked := sdk.NewCoin(coin.Denom, lockedCoins.AmountOf(coin.Denom))
-
-		spendable, hasNeg := sdk.Coins{balance}.SafeSub(locked)
-		if hasNeg {
-			return errorsmod.Wrapf(sdkerrors.ErrInsufficientFunds,
-				"locked amount exceeds account balance funds: %s > %s", locked, balance)
-		}
+		balance := k.GetBalance(ctx, addr, coin.Denom).Amount.BigIntMut()
+		locked := lockedCoins.AmountOf(coin.Denom).BigIntMut()
+		amount := coin.Amount.BigIntMut()
 
-		if _, hasNeg := spendable.SafeSub(coin); hasNeg {
-			if len(spendable) == 0 {
-				spendable = sdk.Coins{sdk.NewCoin(coin.Denom, math.ZeroInt())}
-			}
+		if balance.Cmp(locked.Add(locked, amount)) == -1 {
+			spendable := balance.Sub(balance, locked)
 			return errorsmod.Wrapf(
 				sdkerrors.ErrInsufficientFunds,
-				"spendable balance %s is smaller than %s",
-				spendable, coin,
+				"spendable balance %s%s is smaller than %s%s",
+				spendable, coin.Denom, amount, coin.Denom,
 			)
 		}
 
-		newBalance := balance.Sub(coin)
-
+		newBalance := sdk.NewCoin(coin.Denom, sdkmath.NewIntFromBigIntMut(balance.Sub(balance, amount)))
 		if err := k.setBalance(ctx, addr, newBalance); err != nil {
 			return err
 		}