One thing I can tell you is this. I won't mention the companies name here. But they joined the vBulletin.com
website hosting to keep track of vBulletin board changes because they realized that the most used board out there is vBulletin. So they tend to optimize there servers for it to be used at there host. Which has proved a good move for them in getting mention and recommended all the time at vBulletin which has seen there server grow 10 fold.
They have installed things like
FastCGI and
eAccelerator and on there shared host accounts which is normally only found on
dedicated servers. These are some idea you could use to boost the shared host accounts here by installing the same.