If you're having performance issues while editing, changing your GPU settings (aside from making sure you have up-to-date drivers) isn't going to fix your issue. It's likely that your bottleneck is somewhere other than your GPU and you can find this out by opening the Task Manager and looking at the Performance tab. Is any specific component maxing out at or close to 100% while you're having issues during editing?
Your CPU could be too slow, your drives could be too slow, your footage could be highly compressed and difficult to play back. Maybe you just need to drop your Program monitor to 1/2 resolution.
Please provide a lot more detail about your workflow. What kind of footage are you editing (the exact format, not just MP4, MXF, MOV, etc.)? Do the problems start with just raw footage or only after you apply a lot of effects? Do you use Dynamic Link compositions in Premiere and that's where the performance issue is?
Without knowing anymore information it could very likely be that your footage is highly compressed and you need to be working with lower quality, intraframe proxies as opposed to Long GOP footage that your CPU can't easily decode to play back in real time.