I don't think this is the case because, as I said, a workaround fix to this is opening an empty project and inserting the plugin that is displayed DURING the freeze.
For example, as mentioned, Logic will often freeze on Pro-Q 3 for me (i.e., that plugin is displayed upon the freeze during load). If I open an empty project, create an empty software instrument track, and insert a default stereo Pro-Q 3 instance to that track, then (re-)open the initial project, it will load fine. How would you explain this behavior?