MyISAM is fine - unless you write to a busy table. If that happens, table locking will definitely kill you. In my experience, the InnoDB performance overhead is not an issue, but of course this will vary according to your specific situation. And also of course, InnoDB has other things to consider (need to be smart about the tablespaces, since they won't shrink automatically.)
Don't know Sphinx or what you'll use it for (sounds to me that it's useful for the site's search engine.)
I don't know about anyone else but since Robbie posted about redoing the table the loading speed has really improved for me. Not sure if it's a coincidence and might slow down again, but I hope not!
Well, today the forum seems to be flying. Only takes three or four seconds for a page to load, as opposed to a minute or two that it was a few days ago. Being so new here I thought it was always slow.
"only carefully calculated results from carefully executed procedures" Great work from the SA's. Home page loaded in about three seconds, forums even less. Kudo's and thanks.
Still working on further improvements...thanks for the feedback
Robbie Powell - Site Admin