'Out of application memory' problem

Replying to my own post, an update. I have no idea why, but as a hunch I decided to move/copy all of my motion template folders to a benign storage area that FCP wouldn't know about. Two things happened when I fired FCP back up. Immediately, several of the motion templates subfolders were readied by FCP. Not all of them, but several. Meaning, it added for instance into Titles "Collage Pop , "FX Factory" and a couple of others but not "Bret FX Power tools" and others. I have learned to manage highly related projects within their own individual library, so in my FCP at this moment I have only two very small libraries and none of the projects are using any of those motion templates that were automatically repopulated. SECOND, and more importantly, FCP is creamy smooth again - as I would have expected it to be with such a tiny library.

So, obviously, still a student even though I've been using FCP for 7+ years. What is going on here and why just now did this gremlin pop up?

It's possibly caused by a plugin. In the current FxPlug 3 architecture, non-template plugins run inside the FCP address space. A single error in a single plugin can destabilize or crash FCP. Unfortunately there is no built-in plugin manager or FCP "safe mode" to start with all plugins disabled.

This should be improved with the new FxPlug 4 framework which runs plugins in a separate address space outside of FCP, however plugin developers must re-write the code for that. But it's mandatory for Apple Silicon, so developers are incentivized.

In the meantime your best approach is update all plugins and remove any you no longer need. FxFactory has an easy way to update all plugins from them. Especially update any plugins from CoreMelt. You can update those using their installer page: coremelt.com/pages/downloads

There have been many problems traced to Pixel Film Studio plugins. If possible try removing those or make a test library and copy a project over there, then remove those from that test timeline. Here is how to remove those plugins: https://store.pixelfilmstudios.com/how-to-uninstall-a-plugin/

There is a 3rd-party plugin manager utility that's part of Digital Rebellion's Pro Maintenance Tools, however it's $129: www.digitalrebellion.com/promaintenance/

Great feedback thank you. Right, Apple needs to build a GUI for managing plugins. 

Joema, forgot to follow up on one of the questions buried in my earlier reply. Do you know why and or how FCP decides to  repopulate certain folders and files back into motion templates, even after I've manually removed folders and files? As I said, I had a Finder window open, fired up FCP, and boom, they were  readied in a quick second. Thanks again.