I know from experience that USEO is not CPU intensive but never used the "usercurrency" add-on so not sure.

Also, for example, if you are using a Hoster charging less than 30 cents per GB of Data transfer for your Hosting package, they could be lowering many of your Service levels in order to offer them at that price. And their servers are usually overloaded as well.

Both of these are common tactics used by Hosters competing on price.