I've never seen a shared host offer a PHP accelerator, so I'm sure there's some technical reason as to why they can't offer them.
I seem to get only intermittent delays though. Sometimes the pages load fast, sometimes really slow. Hmmm.
That's pretty typical for a shared host. Because you're sharing the same server with other customers (see below), your load times depend not only on your own traffic, but on the traffic of everyone else as well. So if another site on the same server is experiencing a huge increase in traffic, your site performance will suffer as well. We used to have this issue with Nookipedia, which is why I eventually moved us over to a VPS at Linode. Needless to say, our site's speed is much faster now.
I ran a reverse IP lookup for your wiki, and found that the following sites are also hosted on the same server:
[spoiler="List of Sites on your Server"]
[/spoiler]