Selection - deselection slows program to a halt

[gregors]

I find it difficult to modify a selection (like subtract from it) if there are very many pieces to the selection.

I have a png image about 1200 * 1000 px I use magic wand select globally and get a selection with probably thousands of islands. I want to remove some of these islands and try to deselect with the rectangle tool but after I set the first corner PaintdotNet chokes and it takes litterally several minutes befor I can set the second corner of the rectangle. Forget about trying to draw a deselection with the lasso tool...

Any suggestions?

2,4GHz QuadCore 3,5GB RAM Windows XP

[Ego Eram Reputo]

Windows 7 - 64 bit. Seriously, you're putting a large load on the system with this selection in an image that size. Your system should be able to handle it, but the OS is probably holding you back.