TBP2 on Ubuntu is slow

Hi

I'm running Thunderbird Portable 2.0.0.4 from a portable hard disk on Ubuntu 7.04 (using Wine 0.9.40) and here's the issue I'm facing:

When I first load up TBP, my CPU usage (as seen on System Monitor) goes up to 100% with TBP taking upto 30-40%. If I wait patiently, the window loads, my email downloads and then my CPU usage drops to a normal level. The cycle repeats when I click on a mail in the list or switch the folder or switch to another window.

Up until a couple of days back I was using TBP 1.5 without any such problem, so I'm guessing it's an issue with Thunderbird 2 itself (rather than TBP.)

But anyway, has any one else faced such an issue or has a clue about what could be wrong?