Simple effective VM optimisation

Added a debug flag to the VM which determines if VM output is shown
regardless of the log level set.

vm/vm.go

@@ -16,6 +16,8 @@ type Vm struct {
 	logStr string
 
 	err error
+	// For logging
+	debug bool
 
 	Dbg Debugger
 
@@ -32,7 +34,7 @@ func New(env Environment) *Vm {
 		lt = LogTyDiff
 	}
 
-	return &Vm{env: env, logTy: lt, Recoverable: true}
+	return &Vm{debug: false, env: env, logTy: lt, Recoverable: true}
 }
 
 func (self *Vm) Run(me, caller ContextRef, code []byte, value, gas, price *big.Int, callData []byte) (ret []byte, err error) {
@@ -938,18 +940,22 @@ func (self *Vm) RunPrecompiled(p *PrecompiledAccount, callData []byte, context *
 }
 
 func (self *Vm) Printf(format string, v ...interface{}) VirtualMachine {
+	if self.debug {
 		if self.logTy == LogTyPretty {
 			self.logStr += fmt.Sprintf(format, v...)
 		}
+	}
 
 	return self
 }
 
 func (self *Vm) Endl() VirtualMachine {
+	if self.debug {
 		if self.logTy == LogTyPretty {
 			vmlogger.Debugln(self.logStr)
 			self.logStr = ""
 		}
+	}
 
 	return self
 }