4.0 very slow with XML files

In the release version of 4.0, working with medium-sized XML files is very
slow in VS 2008. I don't recall pre-RC1 builds being anywhere near this
slow.

I have an XML file that is about 800KB, and it literally takes about 5
seconds to get the cursor back after any action (like pressing a key,
clicking the mouse, etc.). This makes the text editor unusable. Turning off
analysis for the file (Ctrl+8) does not improve performance. Disabling
ReSharper brings performance back to normal.

Any ideas?