this is something that has been around Audacity for many versions now and bothered me some times and eventually I registered to post this:
I use Audacity 2.1.0 on Win7.
As already known the Effects menu gets really big when there are many Plugins installed.
When I use it I get the "bug" that after long-clicking the down-Button once I can hover it to scroll really quickly.
This doesn't work for the up-Button and stays until I restart Audacity (Even after re-opening the menu).
This wouldnt be a big problem and actually a nice feature if it would also work for the up-Button
The Quick-fix:
To make this better useable besides creating Categories and a shorter menu I would suggest the behaviour of many other programs (e.g. Firefox):
Enable Mouse-Wheel-Scrolling
I think this would be easy to do (But I don't know if this isn't a problem of GTK+).
Cheers and thanks for the great work,
DG