Yes. Well, at least with 3.4, you are the only one reporting this so far…
Yes. Typically, Audacity projects can get bogged down severely by a feature called smartclips. So what happens, is when you copy a small part of a much much larger clip, that larger clips remains in your project even if you delete it later! (which is common). But just the presence of that clip makes your project larger and slows everything down.
To correct this issue, it is a simple matter to copy your entire project to a new project without the “smartclips”. To this this there are four (4) steps:
Ctrl+A (Select All)
Ctrl+C (Copy)
Ctrl+N (New Project)
Ctrl+V (Paste), when prompted, do NOT past smartclips.
After you save (and close) the new project, make note of the difference in sizes.
But files are same mp3 music files of about the same size. I notice a large time delay in loading mp3 file as compared to previous version of Audacity (v3.3x)