Mabook Pro has serious lagging issues. Please help!

Hi. I recently upgraded to Mojave from High Sierra and noticed almost immediate lag. I had a few issues with high Sierra, but nothing major with the exception of restarts. Anyway, I deleted Mojave, did clean install with Snow Leopard and made my way back to High Sierra 10.13.6. I am still noticing serious lagging. Can't open any of my music projects with Logic or Kontakt or any window without long delays. Even my zoom in and out are very slow.

Here is what I am running.

Macbook Pro 13 inch (mid 2012) 2.9 GHz intel Core i7/memory maxed to 16 gigs

I replaced the internal HD with the much faster Samsung 840 EVO 1TB Internal 2.5.

Here are the some things I tried to do.

Nvidia's website driver for High Sierra. In the manager prefs menu, the ECC says "No driver found."

I also installed Nvidia Cuda Driver Version 410.130 but it says no GPU Detected. Not sure if there is something I need to do in terminal.

Alternatives methods were to install flash, and use Cleanmymac X for maintenance, freeing up memory and malware check. all clean.

I was also thinking about installing JAVASCRIPT, but don't really know what I'm doing. My OS finally stop working and had to open in recovery mode to reinstall High Sierra. Any advice would be much appreciated.