Twitter posted an update recently on the Twitter Status blog indicating they’ve almost squashed all the bugs that have impacted site performance recently.

The site has been sluggish the past couple days, but we’ve been making good progress on some of the more serious bugs.

• We’ve largely resolved the database inconsistency issues that were responsible for a wide range of problems. These include: fluctuating direct message counts and missing updates. Some older updates (from before 3/25) may still not have reappeared. But new updates should no longer be missing.
• Some improvements to follow/unfollow. There are still folks running into problems trying to follow or unfollow users. However, the inconsistencies related to this have improved some and we have more improvements on the way. The biggest issue right now is the latency people encounter when trying to follow; we’re working to resolve that.
• Image uploading for avatars and background images should be much improved
• Users with bounced email addresses can now have us try to send mail again (rather than having to write in). And we’ve resolved a deliverability problem we were having with Hotmail.

There’s still a lot of people running into trouble because of the site slowness. And slowness, itself, is a problem. We’re working hard on these issues and will post more as we make progress.