Logic X suddenly running extremely slow despite low cpu load

Howdy, here's another Logic run slow post! None of the solutions in other posts have worked for me, so here I am...

System: specs are shown in screenshots below, but it's a macbook pro 16" 2019 intel model purchased in 2021 with every internal upgrade maxed out aside from HD space. I do not run an external HD except for backups/storage. I do not use an external monitor. Logic and OSX on my system are old, but upgrading isn't really an option. More on that below. Happy to share any additional info if needed.

Problem: Logic is running extremely slow. Not just the GUI, but it's responses to any of my inputs (mute, solo, play, stop, arm, etc) all take 1-5seconds. The framerate of volume and all effects displays is also extremely slow. One thing to note is that this is NOT the case when I don't have Logic selected. If I have another window open w/ Logic running in the background, framerate is perfect until I select Logic again. Then it goes to poops. This issue appeared suddenly with no changes, no new software, no new hardware, no new settings, nothing.

The type of project makes no difference. Large, small, brand new, plugins, no plugins. They all have the same problem and show no difference in the severity of the issue.

My system specs are in the screenshots below. More than enough cpu power and ram, and activity monitor doesn't show high use by anything. Highest is Logic hitting in the mid-30%s, otherwise sitting below 10%. Keep in mind that on my older osx, these percentages are of individual cores, not of the total cpu capacity. So that's 10ish - 35ish% of one core.

The outdated versions: I'm running an older version of Logic (10.6.2) on an older osx (10.15.7 Catalina). Updating these does not appear to be an option for me because I will loose compatibility with an older version of another key software that I use regularly. I need it's older version for how it interacts with Logic, or I loose access to years of older session files that worked via rewire. Upgrading logic requires upgrading osx, which effectively means I lose access years of sessions. I've got to try and make this work the way it had been just a few days ago with the older versions I've been running with no issue for some the last couple years.

What I've tried: computer reset, pram reset, reisnstall the osx I'm using, shutting off all other applications, initializing Logic's preference settings, disabling plugins that Logic doesn't like (again, none of these are new and were all working fine prior to the slow-down), talking to the genius bar for 1.5 hours, sacrificing small animal on a pentagram. And now, you guys!

If anyone has any input that might help, it would be awfully swell of you to share!