Premiere Pro Lag

Hi- just updated premiere pro to 2018 version. I'm still very new to all of this so I could use some help.

Also updated my mac. Experiencing a horrible lag that is keeping me from being able to edit. I minimized the quality to 1/4, cleared the cache, restarted my computer several times, updated, (not able to change video preview because it is greyed out), optimized as much memory as I could towards premiere pro (almost all of it)....and just dont know what else to do! The video is still totally lagging, none of this helped at all. I have to transfer everything to my hard drive to use with my new macbook pro anyway in the next few days. Should I just see if it will work better on this other computer? Or is there some issue that needs to be fixed? Thanks for your time.