What is my mistake?

BenchmarkTest.groovy

@Grab( 'com.googlecode.gbench:gbench:0.3.0-groovy-2.0' )
import gbench.*

def i = 0
new BenchmarkBuilder().run( measureCpuTime:true ) {
  'TEST:' {
     1000000.times{i?.toLong() ? i?.toLong() : null}
  }

  'TEST:' {
     1000000.times{i?.toLong() ? i?.toLong() : null}
  } 
}.prettyPrint()


/**
    Me: Why Do I have a different result for the same code?
     
    Environment
    ===========
    * Groovy: 2.4.0
    * JVM: Java HotSpot(TM) 64-Bit Server VM (21.0-b17, Oracle Corporation)
        * JRE: 1.7.0
        * Total Memory: 127 MB
        * Maximum Memory: 127 MB
    * OS: Windows 7 (6.1, amd64) 
    
    Options
    =======
    * Warm Up: Auto 
    * CPU Time Measurement: On
    
                user  system        cpu       real
    
    TEST:  134550862       0  134550862  133996441
    TEST:  140400900       0  140400900  140462451
*/