My Thunderbird has slowed down horribly since I did the recent 4 to 5 upgrade. Emails with attachments now take anywhere from 10-60 seconds to open, not counting actually opening the attachment.
I use Thunderbird 3.0.2 but I didn’t find any slow down…
Do you have a link for the free 4.8 download? I’d like to reload it again to see whether it’s avast or Thunderbird that’s the problem.
No problem here either. Do you have a secure (SSL) account set up in Thunderbird, like gmail? You may just need to configure it.