Shap,
We're also hosted on Jupiter and absolutely no slowdowns here either...
I've just checked your tour & members area and you are right , members are loading extremely slow but I think your bottle neck caused by Mysql and/or PHP code.. For example updates.php (queries all database from what I've seen) is the slowest loading page.
You may try one of those:
* add query_cache_size=128M config command to MySQL (Depending on your memory size on the box) so it'll cache those static repeating queries (like your home page or updates page) and returns cached results in much shorter time.
* Make sure all your mysql queries takes place in a single connection call
* Make sure your queries request just the used data (not something like "SELECT * FROM table")
* You should also consider Zend Performance suite if you have funds.
There are more points you can check but those were the most significant ones..
I hope this helps
