My premiere pro is lagging

As another user, no clue. Did you update Premiere Pro? Change media or effects? Could be a number of things, but at any rate, that rig ... is old, very old.

Sad to say, replacing it. Or stay on an earlier release of Premiere Pro. We first started with computers in our business about 1988. I don't know how many we've been through.

For stills, we could start with a slightly above middle Pro quality, and then get about six years before replacing.

When I switched to Pro video that changed. I get about a medium high spec rig for Pro use, and hope for 3-4 years.

My old desktop is my backup rig now. It's an 8 core unit with 32GB of RAM, and a 1060 GPU.

My work desktop is a 32 core Ryzen 3960x w 128GB of RAM, and a 2080Ti. One on-board mounted Nvme SSD for OS and programs, a second for all cache files. And 8 internal SSD drives for media, projects, exports and such. A couple 16TB spinner drives.

I'm about a year and a half into use. I knew the GPU would need updating at some point and that's gonna be this spring. I work for, with, and teach pro colorists who are mostly based in Resolve. I've been tasked with more training production and Resolve eats GPU vRAM for snacks. Probably a 4000 series card this time.

It's all part of the cost of doing business. But still, ouch.

That 4 core CPU is a full decade old now. Last Intel support was listed as in 2017, six years ago. It's an old rig that no one supports anymore.

Sorry, but that's Life in computer terms.