diff --git a/chain/vm/runtime.go b/chain/vm/runtime.go
index eb4476718..72dd413ed 100644
--- a/chain/vm/runtime.go
+++ b/chain/vm/runtime.go
@@ -459,8 +459,10 @@ func (rt *Runtime) stateCommit(oldh, newh cid.Cid) aerrors.ActorError {
 }
 
 func (rt *Runtime) finilizeGasTracing() {
-	if rt.lastGasCharge != nil {
-		rt.lastGasCharge.TimeTaken = time.Since(rt.lastGasChargeTime)
+	if enableTracing {
+		if rt.lastGasCharge != nil {
+			rt.lastGasCharge.TimeTaken = time.Since(rt.lastGasChargeTime)
+		}
 	}
 }
 
@@ -489,35 +491,39 @@ func (rt *Runtime) chargeGasFunc(skip int) func(GasCharge) {
 
 }
 
+var enableTracing = false
+
 func (rt *Runtime) chargeGasInternal(gas GasCharge, skip int) aerrors.ActorError {
 	toUse := gas.Total()
-	var callers [10]uintptr
+	if enableTracing {
+		var callers [10]uintptr
 
-	cout := 0 //gruntime.Callers(2+skip, callers[:])
+		cout := 0 //gruntime.Callers(2+skip, callers[:])
 
-	now := build.Clock.Now()
-	if rt.lastGasCharge != nil {
-		rt.lastGasCharge.TimeTaken = now.Sub(rt.lastGasChargeTime)
+		now := build.Clock.Now()
+		if rt.lastGasCharge != nil {
+			rt.lastGasCharge.TimeTaken = now.Sub(rt.lastGasChargeTime)
+		}
+
+		gasTrace := types.GasTrace{
+			Name:  gas.Name,
+			Extra: gas.Extra,
+
+			TotalGas:   toUse,
+			ComputeGas: gas.ComputeGas,
+			StorageGas: gas.StorageGas,
+
+			TotalVirtualGas:   gas.VirtualCompute*GasComputeMulti + gas.VirtualStorage*GasStorageMulti,
+			VirtualComputeGas: gas.VirtualCompute,
+			VirtualStorageGas: gas.VirtualStorage,
+
+			Callers: callers[:cout],
+		}
+		rt.executionTrace.GasCharges = append(rt.executionTrace.GasCharges, &gasTrace)
+		rt.lastGasChargeTime = now
+		rt.lastGasCharge = &gasTrace
 	}
 
-	gasTrace := types.GasTrace{
-		Name:  gas.Name,
-		Extra: gas.Extra,
-
-		TotalGas:   toUse,
-		ComputeGas: gas.ComputeGas,
-		StorageGas: gas.StorageGas,
-
-		TotalVirtualGas:   gas.VirtualCompute*GasComputeMulti + gas.VirtualStorage*GasStorageMulti,
-		VirtualComputeGas: gas.VirtualCompute,
-		VirtualStorageGas: gas.VirtualStorage,
-
-		Callers: callers[:cout],
-	}
-	rt.executionTrace.GasCharges = append(rt.executionTrace.GasCharges, &gasTrace)
-	rt.lastGasChargeTime = now
-	rt.lastGasCharge = &gasTrace
-
 	// overflow safe
 	if rt.gasUsed > rt.gasAvailable-toUse {
 		rt.gasUsed = rt.gasAvailable
diff --git a/chain/vm/vm.go b/chain/vm/vm.go
index 54ea47698..c566ec1eb 100644
--- a/chain/vm/vm.go
+++ b/chain/vm/vm.go
@@ -227,14 +227,21 @@ func (vm *VM) send(ctx context.Context, msg *types.Message, parent *Runtime,
 	}
 
 	rt := vm.makeRuntime(ctx, msg, origin, on, gasUsed, nac)
-	rt.lastGasChargeTime = start
+	if enableTracing {
+		rt.lastGasChargeTime = start
+		if parent != nil {
+			rt.lastGasChargeTime = parent.lastGasChargeTime
+			rt.lastGasCharge = parent.lastGasCharge
+			defer func() {
+				parent.lastGasChargeTime = rt.lastGasChargeTime
+				parent.lastGasCharge = rt.lastGasCharge
+			}()
+		}
+	}
+
 	if parent != nil {
-		rt.lastGasChargeTime = parent.lastGasChargeTime
-		rt.lastGasCharge = parent.lastGasCharge
 		defer func() {
-			parent.gasUsed = rt.gasUsed
-			parent.lastGasChargeTime = rt.lastGasChargeTime
-			parent.lastGasCharge = rt.lastGasCharge
+			parent.gasUsed += rt.gasUsed
 		}()
 	}
 	if gasCharge != nil {
diff --git a/cmd/lotus-bench/import.go b/cmd/lotus-bench/import.go
index b535ed96c..c3554f939 100644
--- a/cmd/lotus-bench/import.go
+++ b/cmd/lotus-bench/import.go
@@ -119,33 +119,37 @@ var importBenchCmd = &cli.Command{
 			tdir = tmp
 		}
 
-		bdgOpt := badger.DefaultOptions
-		bdgOpt.GcInterval = 0
-		bdgOpt.Options = bdg.DefaultOptions("")
-		bdgOpt.Options.SyncWrites = false
-		bdgOpt.Options.Truncate = true
-		bdgOpt.Options.DetectConflicts = false
-
-		cache := 512
-		bds, err := pebbleds.NewDatastore(tdir, &pebble.Options{
-			// Pebble has a single combined cache area and the write
-			// buffers are taken from this too. Assign all available
-			// memory allowance for cache.
-			Cache: pebble.NewCache(int64(cache * 1024 * 1024)),
-			// The size of memory table(as well as the write buffer).
-			// Note, there may have more than two memory tables in the system.
-			// MemTableStopWritesThreshold can be configured to avoid the memory abuse.
-			MemTableSize: cache * 1024 * 1024 / 4,
-			// The default compaction concurrency(1 thread),
-			// Here use all available CPUs for faster compaction.
-			MaxConcurrentCompactions: runtime.NumCPU(),
-			// Per-level options. Options for at least one level must be specified. The
-			// options for the last level are used for all subsequent levels.
-			Levels: []pebble.LevelOptions{
-				{TargetFileSize: 2 * 1024 * 1024, FilterPolicy: bloom.FilterPolicy(10)},
-			},
-			Logger: log,
-		})
+		var bds datastore.Batching
+		if false {
+			cache := 512
+			bds, err = pebbleds.NewDatastore(tdir, &pebble.Options{
+				// Pebble has a single combined cache area and the write
+				// buffers are taken from this too. Assign all available
+				// memory allowance for cache.
+				Cache: pebble.NewCache(int64(cache * 1024 * 1024)),
+				// The size of memory table(as well as the write buffer).
+				// Note, there may have more than two memory tables in the system.
+				// MemTableStopWritesThreshold can be configured to avoid the memory abuse.
+				MemTableSize: cache * 1024 * 1024 / 4,
+				// The default compaction concurrency(1 thread),
+				// Here use all available CPUs for faster compaction.
+				MaxConcurrentCompactions: runtime.NumCPU(),
+				// Per-level options. Options for at least one level must be specified. The
+				// options for the last level are used for all subsequent levels.
+				Levels: []pebble.LevelOptions{
+					{TargetFileSize: 2 * 1024 * 1024, FilterPolicy: bloom.FilterPolicy(10)},
+				},
+				Logger: log,
+			})
+		} else {
+			bdgOpt := badger.DefaultOptions
+			bdgOpt.GcInterval = 0
+			bdgOpt.Options = bdg.DefaultOptions("")
+			bdgOpt.Options.SyncWrites = false
+			bdgOpt.Options.Truncate = true
+			bdgOpt.Options.DetectConflicts = false
+			bds, err = badger.NewDatastore(tdir, &bdgOpt)
+		}
 		if err != nil {
 			return err
 		}