That would explain a lot of the why I don’t see any issues and what I have been asking for on many similar threads. I can’t file bug reports if I don’t know how to make it crash.
I have no need to make icons larger as I don’t use them. I open everything through Spotlight or list view sorted by Date Added.
I’ve never had a problem with Screen Sharing, though it is always viewing the M1 from MBP.
I don’t have any issues with the Applications folder, but if you mean via screen sharing, I don’t have a need to do that so would not have noticed.
I’ve always assumed SMB access is slow. I don’t know what fast would look like.
There is another post where the OP has very good documentation on slow external drive access, and is worse for APFS HDD. I don’t remember if HFS+ is affected at all.
Finder has always had a problem with large number of files and deeply nested folders. It really isn’t a suitable file browser for those situations; never has been. If it is worse in Sonoma, maybe they tried to fix that.