Then I started to wonder; Is this just the case of a 32-bit .dll being in the wrong folder, being scanned and failing? For all I know that failing line might have been there all the time.
For more information, I don’t think the slowdown is related to the detection of misplaced 32bit plugins.
Just to check, I created and saved a gig file with several 64bit plugins, then copied the 32bit versions of these plugins to the 64bit folder.
Loading the gig file was not slowed down and of course I found the 32bit plugins reported failed.