refactor!: instantiate client.TxConfig once for simulations (#15875)

types/module/simulation.go

@@ -7,6 +7,7 @@ import (
 	"time"
 
 	sdkmath "cosmossdk.io/math"
+	"github.com/cosmos/cosmos-sdk/client"
 	"github.com/cosmos/cosmos-sdk/codec"
 	"github.com/cosmos/cosmos-sdk/types/simulation"
 )
@@ -142,6 +143,7 @@ func (sm *SimulationManager) WeightedOperations(simState SimulationState) []simu
 type SimulationState struct {
 	AppParams         simulation.AppParams
 	Cdc               codec.JSONCodec                // application codec
+	TxConfig          client.TxConfig                // Shared TxConfig; this is expensive to create and stateless, so create it once up front.
 	Rand              *rand.Rand                     // random number
 	GenState          map[string]json.RawMessage     // genesis state
 	Accounts          []simulation.Account           // simulation accounts