Is there any reason why you're running 32-bit?
No, however, I checked with the developer and there is no speed difference between 32 and 64 bit versions so it seems there won't be any improvement in moving to the 64 bit version.
Perhaps clear the thumbnail cache and try again.
Thank you for the hint - just did it and nothing changed.
The thing is that the slowness is not only in viewing thumbnails but also in scrolling files/folders while in the details view (standard columns, not many files, solid background color / no stripe). The thing I noticed is that FC runs faster if launched in as the administrator.