What hardware are you running? OP was running a virtual machine with "4GB of RAM, 4 cores and a 32GB fixed disk for each build". I do wonder how if they only d

What hardware are you running? OP was running a virtual machine with "4GB of RAM, 4 cores and a 32GB fixed disk for each build". I do wonder how if they only did one run per test or multiple, since n=1 will mean noise can mess with your results.