Complex parts with many feature can sometimes increase the rebuild time. In SolidWorks 2012 and higher V, you can reduce the rebuild time and raise the performance of your workstation by using the FreezeBar (or the Freeze Feature).
This tutorial will show you how to activate and work with the FreezeBar.
You can work with this feature to lock some feature in the part, that are complete and don't need to rebuild.
Answered with a tutorial: https://grabcad.com/tutorials/how-you-can-reduce-the-rebuild-time-in-solidworks-freeze-bar