Why is compile taking 4 times longer under VM?

[mraynelson]

Workstation Pro 14

CPU: Intel i9 7900xe

Host: Windows 10, 1TB SSD

Guest: Windows XP Professional x86, 1CPU, 16 cores, 3 GB RAM, 128 GB IDE single file dynamic size (not preallocated)

BIOS has Intel VT-x enabled in BIOS

Compiled files are on local VM "disk", not on network or share.

Why would compile take 4 times longer on VM? This seems highly unreasonable. As a sanity check, I ran the same compile under a VirtualBox VM on a slower machine and found it to be twice as fast as this Workstation Pro VM.

I would appreciate any ideas on how to fix this.

Thanks.

[continuum]

If I remember right the max amount of cores/cpus that Windows XP can handle is 2.
So very likely assigning 16 cores the your VM is absolutely contra productive.
Try to assign just 1 CPU with 2 cores and check the compilation times again.

[mraynelson]

Indeed, assigning 2 cores rather than 16 cut the total build time almost in half. So total compile time is now about 2.5 times longer under VM.

Couple of other notes:

No snapshots, both host and guest disks are defragmented.

Thanks for your response.

[continuum]

In my experience XP performs best with just a single CPU and 2 GB RAM - but that may vary depending on the application you use.