Huge differences on Memory benchmarks with different benchmark settings (VM)

[TomCat]

Hello guys,

I'm using PerformanceTest to make some benchmarks on VirtualBox.
When I run the Memory test on short test duration and one iteration I have the RAM speed almost 3 times slower than if I run the same test again but with medium test duration and 4 test iterations.
More of that, this hapens only on VirtualBox, when I test on the physical machine the results are close enough.

Any ideas why this happens?

[David (PassMark)]

Maybe there is extra overhead in the VM when it need to allocate a large amount of RAM.

When the test duration is short, the overhead would make up a significant part of the test's execution time.

As the test duration gets longer and you increase iterations, the (fixed time) overhead makes up a smaller and smaller part of the test period.