My GMail is consistently faster than my corporate Outlook, on the LAN, in a company with ~200 employees. This has been true of every company I've worked at.

I don't currently have Outlook/Exchange. I suppose if I did it's possible that gmail would seem much nicer to me than it currently does.

My experiences with gmail are very positive. I have about about 10GB of mail across 4 gmail/apps accounts with about 100k messages, and the performance is almost always instant (search, send, read, file). Furthermore if I travel to the other side of the world (which I do 3-4 times a year) then it continues to offer a quality level of service. I've never seen any in-house system get close to what I get from gmail.

You and @VikingCoder make similar points. I suppose it's possible that I suffer slower gmail than you guys (I am mostly using a company 'apps' account, maybe that matters).

It's also possible that you find gmail awesome because you're comparing it to an in-house system. I'm not. I'm comparing it to Asana, Quora, StackOverflow, or even other some GOOG products. In my world Gmail lines up with JIRA more often than with the tools whose performance consistently delight me.

I use Google Apps at work too and it's as fast as my regular Gmail account was.

Maybe it's the JS? Gmail is very code heavy and my laptop sometimes can't keep up.

You should try to decrease the number of conversations per page to 20 or less, that will help.