Hi guys...sorry I didn't get back...sometimes work has to take precident. I haven't had much time to research all you guys have contributed, but here's where I stand. I looked at the performance stats and from what I can see, GPU load never goes above 10%. Memory doesn't get maxed out, and neither does disk. What does get high is CPU usage, but I need to look deeper into this. However, lets say right now I'm not going to address upgrades yet.
BTW...if it matters, when I said 4 cameras...they are GoPro9s. I don't know if they have an influence on PP performance.
HOWEVER...what I am going to look into is using proxies. Never have before... between you and me, I'm only in the video world for about 2 months...10+ years in the stills world)
Warren is a very experienced pro, his advice is very good btw. I'll just add a bit more and/or different perspective.
The only downsides to use of proxies is a bit of time with the computer making them while (hopefully) you do something else. And a bit of space in disk storage.
Proxies are a heavily used process in video post. I also came out of a stills background. The image files there are tiny compared to what we deal with in video. So the processes have to be different just from a practical perspective.
For many people, setting the computer to make proxies say overnight for tomorrow's work is slick and all they need do. Finish the project, you dump the proxies as they can be recreated if you ever need to.
I know others that (like in Warren's example) transcode overnight instead of proxies. And work the project from the t-codes, using an intraframe codec like DNxHD/R, Cineform, or ProRes. Much larger files on disk, but they edit better.
And again, they dump the t-codes after the project is over because they can always recreate them from the more heavily compressed original files.
Something to know up-front when using the Premiere Pro Proxy Workflow: Do not import and use Proxy files directly. Always use the Full Resolution clips with Proxy files attached. It's okay to take the Full Resolution clips offline, but not okay to use the Proxy files in place of the Full Resoultion clips.