What did you do to this app? I have been using it for years and then I updated to 3.1.9 Now it runs like it was written by (the ones whose name shall not be written nor spoken).
It constantly is re-downloading all the email messages. Click on something it clears the window completely for no reason and takes for ever to redraw. It is banging hard on my processors.
I am running XP Pro SP3 (32bit) Version 2002 on an Intel Core 2 Quad CPU Q8200 @2.33 GHz with 4 gigs Ram, Nvidia video card, 4T hard storage with >2T free.
It's running perfectly fine here. I use it locally (portable version installed on a hdd) and portable on different machines. I did not encounter any problems so far. My base configuration doesn't differ too much from yours.
Did you try to reinstall? Or a clean installation without any extensions? I think we need more information to offer some help...
Anyway - did you read this?