I’ve tried Live Writer myself recently and liked it a lot more than I did when I tried it about a year ago (I think). I wrote a few posts with it. But, I’m back to using the WordPress interface, partially because it’s more portable (I can switch draft writing from one computer to another), and partially because 2.5′s visual editor has much improved! (Actually I switched back before that, but it’s keeping me from trying Live Writer again right away.)

The speed issue is interesting though. Are you pinging various update services from WordPress? Or are you just doing so through Live Writer, or is is pinging set up in WordPress as well? In WordPress under Options (Settings in 2.5)->Writing the list of RPC services to ping is found at the bottom of that page. Windows Live Writer has a similar set of options. If WordPress doesn’t have any or many services (or the right ones), you may be relying on services like Google Blogsearch/Google Reader and others to crawl your feed on their time, causing a delay.