If you tried it right after we added Yahoo Mail support, that must have been 2008. We made a ton of performance improvements in early 2009. I talked about that process, and the fun of developing in Outlook, here: http://blog.adamsmith.cc/2009/04/investing-a-million-bucks-i...

folks on Outlook 2007 will also find a huge OL performance boost from upgrading to SP2, wherein the fixed about thirty Outlook perf bugs, some of which can be tickled by their addin API's!