Hello,
I've mentioned this before on here, but I can't find the post. Here goes.
Open Task Manager and see what's going on in the Performance tab. If you are not thrashing the CPU and there is some available memory (don't worry too much about SQL Server taking up a load of memory, it reserves it and handles it when the kernel wants some more), it's probably the hard disk that's causing the issue. But we'll check.
Open Task Manager -> Resource Monitor and check the disk usage (Disk tab).
Check the general activity in the graphs on the right, and if it is all green, it's running at max. Check the culprit by doing the following.
In 'Disk Activity', select order by Total (B/sec) and see what (if anything) is working the drive. If SQL Server is up there, that's most likely your problem. Also note under the storage pane, how long the disk queue length is. This is essentially an indication of how long stuff is waiting to be written.
Ok, if you now suspect SQL Server is hogging resources, you'll need to do a few things to trim it down a little bit. You could run some defrag stuff, but a lot of the tables/indexes are too small for SQL to bother about. The most likely thing to do to fix it is to do a shrink database. This [in my experience] will have a dramatic effect on performance.
If it works, cool. Let us know so other peeps can try it :)
EDIT: I've just opened your site and it actually seems ok for speed?