The fact that Open GL is greyed out is normal. It is always greyed out any time that you have any SolidWorks files open. Doesn't matter what graphics card you have. Is it checked? If it is, you can close all of your SolidWorks files and then see if you can uncheck it.
I doubt that it will matter whether it is checked or unchecked if your problem is slow rebuild times. That is mostly driven by your CPU, not your graphics card.
I resolved the issue I was having. Solidworks wasn't recognizing my laptop's GPU because my laptop BIOS GPU setting was in dynamic mode (I have a switchable graphics card). I changed the setting to fixed mode, and now the Open GL is not greyed out and I can uncheck it. My Solidworks runs well now.