I've been a long time user of yahoo instant messenger. So I've upgraded it a few times through the years. The performance of the application has slowly degraded through time. Microsoft doesn't have a monopoly on that phenomenon.
So why did I upgrade to the beta? Well, I had the false hopes that the latest version would do a better job on my laptop, which constantly bounces between a wireless and wired connection and the constant docking and undocking that I go through at work. The version I used could be counted on to repeatedly hang and just lock up.
So I upgraded! Dumb.
The UI feels substantially slower. I can see the repainting as I scroll around in the contact list. It's not like I'm running an old school pentium at 50 MHz. I have a respectable thinkpad thank you. When I was looking at the task manager process list in Windows, I noticed that my process takes up a whopping 40 megs.
That's more than IE and Firefox combined! Good lord. Do the programmers have no pride?
Comfortable for the programmer. Just not for the user.