Sometimes, my website (using Joomla) takes FOREVER to load. The website is: Islamic Forum Why does it take forever to load sometimes? I'm using lunarpages shared hosting at the moment.
Most probably highly oversold server from them. Have you asked them about this ?? Any particular time when you are getting such issue ??
Well, they might be running some kind of server Backup at that time. Causing high server load and overall slowdown. But if it's becoming frequent issue, then you should start looking for your new home.
You can follow my signature On a serious note, I cant say much as I do not know about your requirements. Let me know what they are (via PM) so I can suggest you something. Have you received any reply from your current host?
Sometimes the problems are from the site itself. Js, image and bad script/code could become a reason why your site slow to load. As for hosting, I would suggest not to go for "unlimited" plan. Thats nonsense.
You could install Firebug for firefox: http://getfirebug.com/ together with Page Speed: http://code.google.com/speed/page-speed/ and you'll get a good idea where to start looking.