Please describe the problem:
When you have quite a lot of selection areas, especially when you use the 'Fuzzy Select Tool', the CPU usage becomes very high and the redraw of menus stops. 

Steps to reproduce:
1. Create a new image with a white background 1200x600
2. Use the paintbrush with a black pen and draw overlapping squiggles over the screen.
3. Use the fuzzy select tool, hold down shift, and select many areas to build up a complex selection.


Actual results:
CPU usage climbs with each selection, eventually to the point that if you try to access any menu operations, the drop down menu does not draw (only the border appears).

Expected results:
The selection should not use up so much CPU.

Does this happen every time?
Yes

Other information:
If you set the Marching Ants (File | Preferences | Image Windows | Marching ants speed) to 600, then the CPU usage decreases significantly and the menus work as per normal. This was under Vista (Ultimate) with 4GB Ram and Core 2 Duo 2GHz.