Re: Gravatar redirect chains cause too much load time
The Gravatar caching idea can be implemented via a plugin as far as I can see. I don’t think there is anything specifically required in the BP core that isn’t already available to use. Maybe I’ll take a stab at it.
As for debugging load times, you need to use tools like YSlow, Google Page Speed, or the built in page load timers in Firebug (Net) or Safari Developer Tools. These can help you visualize what is taking longer to load. There’s lots of information out there on how to improve page load times (in general, not specific for BP) but much of it requires moving away from some of the features we all like/want (like avatars, child themes, javascript/AJAX, etc.). 
The other alternative is to pay big bucks for ultra high performance hosting with built in CDN, etc. 
