I've spend hours reading through postings about slow performance of WordPress 2.3.1. I have a problem with speed as well. Not with the admin functions, those are lightening fast. My problem is that anyone trying to read my blog gives up because the pages load so slow. If I've broken a post using "continue reading" to give visibility to as many on a page as I can, it just took my friend (using a different ISP than me) 1.5 MINUTES to get the page to load to continue reading. It does the same thing when I access it outside of the admin access. I've deactivated all of my plug-ins (there were only 2), I've checked with my ISP and there are no issues there. I do not have much traffic at all as I am just getting started. Only 1 comment so far. I have no heavy duty database access going on. Oh, and I switch to the default theme just in case. No change.
I was on the version that Yahoo provides when I started and it was very fast. I upgraded to be able to use widgets in my sidebar. At this point I'd take the old version back in a heart beat just to allow people to actually read the blog.
I may have missed something in the hundreds of postings on speed problems. If I have, please let me know what you think I should try.