Premiere Project and Sequence really Lags

I have been working on a feature length doc in Premiere, and recently had to transfer the whole project from a 4TB drive to a 5TB drive (both USB C Lacie drives). Since then, I have experienced really slow performance from premiere when working on this project, in terms of effects control panels is laggy, 1-2 second lag between hitting play and playback starting, save takes 2-3 times longer than it used to, video preview doesn't follow when scrubbing, video thumbnails take ages to load in timeline.

Premiere and my computer don't lag when I open other smaller projects, and even lags much less when I am working in a sequence with much less going on (like a trailer sequence for example). I have cleared cache files, turned off growing files refresh, ran first aid on my hard drive, removed un-needed media from my project file, reinstalled premiere, restarted my computer, duplicated the project, renamed it and opened the new project file, nothing has worked.

Video playback isn't the problem here, I don't have a ton of dropped frames, once playback starts.

Specs
2018 MBP

32GB RAM

2.9 ghz quad core i9 processor

Pro Vega 20 4GB graphics card

Premiere Pro CC 2019, fully up to date

Footage:

Mostly Cinema 4K, C-Log profile Mkv files from Canon c300mkii

Proxies: Custom-wide Quicktime 720p proxies

A good amount of archival footage of various sizes all .mov or .mp4

Trying to figure out how to clean it up and make it smoother, or if I just have to deal with the unbelievable size of the project as an impediment to expediency.

Thanks for your advice in advance