Please help me speed up my site.

I am running a wordpress multisite for our company. blogchrysalis.com The main blog is open to the public but the "House Blogs" are only open to members for privacy reasons. The blogs are being hosted at bluehost.

I have repaired the tables etc. and the speed did improve some but within a week or so I am running slowly again. Is this a bluehost issue? A tables issue? A I am not running the correct plugins issue? Or like most things an all of the above issue?

Would somebody give me some advice to get my site running fast and smooth. I would appreciate it. Even the wp-admin area runs slowly so I am thinking it is not a theme issue per se.

Any help would be greatly appreciated. I have thought about gzip etc but I read conflicting reports about which is best etc.

Thanks in advance for your time!