I got the same problem with performance.
My PC configuration is:
At work:
Windows XP Pro sp2
Pentium 4 3GHz
RAM 512 Mb
and at home
Windows XP home sp3
Pentium 4 3.2GHz
RAM 4Gb
the Fences are causing significant slowdown on the system.
Normally I ran thre programs at the same time : Lightroom, Firefox and Winamp.
At this combination I cannot access desktop fast, it takes forever to display it.
and anything I do is very slugish.
I have 72 icons and 7 fences
Once I uninstall the Fences the system flies.
I cannot accept the idea to limit the number of Fences to 3. It is killing the idea of Fences if they have to be limited.
Sorry to tell, but I have to uninstall Fences on both machines and wait if there is a resolution. I love fences, it makes the desktop so neat.