Judging by the suspension history on your account, the slowness itself is being caused by something on your account - high resource suspensions are a direct result of utilizing too much CPU/Ram for an extended period of time, which is an indication that your script is simply trying to do too much.
I've seen a ton of sites on x10 and most run very well. The ones that don't tend to have many plugins installed (such as your wordpress install, which has 17 different ones), or are just poorly coded to start with. In your case, I'm going to bet one of the plugins is causing it.