Created Issue: version 2.0.4 is slow [7423]

Hi,

Some customers tell me that the image browser of version 2.0.4 was slower.

So i have made some investigation.

And i have seen the image browser is fast when he load (after click on image icon).
+/- 200 ms

But when a postback occurs in the image browser (for exemple, click on upload a new file) is is slow
+/- 2 seconds

I have seen the viewstate is littlebit big (65 kb), but i am not sure of this is realy the raison for so much slower.