[Qt-creator] OT: long build time

[Duane]

Qt 4.8.4.  Creator 3.2.1  Everything is 32 bit.

I have a couple of projects that are built on Windows (MSVC8 with Qt 
integration), Fedora 16 and Fedora 20.  The two Linux boxes are in 
virtual machines using Oracle Virtual Box.  The build time for a full 
rebuild on Windows is 3 minutes.  The build time for both Linux boxes is 
15 minutes.

This is probably off topic since it could be due to the VM but I'm 
looking for any suggestions from people that have dealt with something 
similar.  This seems to be the case for GUI projects.  Projects that I 
have that use only qtcore don't seem to have this issue.

Any suggestions for optimizing Creator or the VM?  I have the VMs 
configured to use both of my cores and half the 4G or ram.