What should I look for when investigating load time issues?

We are currently not using .pdm and forecast doesn't look good for the future.  However, I need to solve a dilemma within our companies computers as it pertains to load times on the same assemblies.  As you can see on the chart I have listed, we have very similar computers with a wide range of load times on the same exact assemblies.  I started by looking at processor and ram, but have very scattered results there.  Is there anything else I should be looking at?  We all run Solidworks Rx and restart computers on a daily basis but thats about it for maintenance.

Thanks,

Ken

SolidworksAdministration