Wilddrums: Thanks for your reply.
OS=Mojave 10.14.3
Logic Pro X=10.4.4
New computer restored from Time Machine backup. Logic Pro is working flawlessly with "new" projects. No issues with plugins. I have a massive number of third party plugins mostly run with Kontakt 5 and Kontakt 6. Kontakt presents no issues in new projects. All third party plugins are functioning properly.
I have deleted and reinstalled Logic from the app store. Haven't done anything with configuration files or resetting preferences. Have exhausted all alternatives in setting buffers within Logic - but Logic normally hard-freezes before I can execute the changes.
Open old project. Wait a bit for plugins and instruments to load. All 8 cpu cores suddenly shoot to maxxed out (no warning) and the entire computer is locked up. Mouse pointer will move, but very slowly and long after I've actually moved it. The only remedy is to hold the power button until the computer turns off. Restart and everything is fine until I load one of these older, HUGE projects in Logic.
I'm baffled. I've read every scrap of advice I can find to remedy this problem.
I have more RAM on the way to bump the computer up to at least 32gb. Hoping that solves the issue. Next step will be to import the tracks from the old project into a new one.
Any input appreciated.
Thanks!
Tim