I just got the Gmail Chat upgrade. It's really nice. It actually works really well considering that I'm logged into Google Talk at the same time. It understands that I've sent someone a message from a particular location, only directs their replies to that location, etc. It also logs chats in Gmail, which I like. I would prefer they be stored there instead of on my work harddisk, frankly.
However, this upgrade has made Gmail slower, again. I'm running in Firefox on a monster PC at work (dual 3.4 ghz xeon, 64-bit windows, 4G of ram). It's popping up windows all over the place that seem kind of pokey. The presence of the chat window itself just seems to be slightly slowing things down a little bit.
Meanwhile, I was looking at a news story on Marketwatch.com this morning, who have cleverly made it so stock quotes update live while you read the story. That's nice and clever, but again it's just making my webpage slower.
Softimage XSI, a 3D application, allows you to script in Python or JScript, thanks to exposing a COM interface. Even with the extra COM layer, I ran some tests that showed Python to be about 3x faster than JScript. And my test was mostly just making calls into the app, with a few inner loops to do some calculations.