Is this not amazing that every host blames your software for the problem?
Well, at some point a site will hit limits and will need to be moved to a VPS or a Dedicated Server; it's just not fair to small sites that don't use resources to have a couple of busy sites kill resources
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When I was working for my old webhost I had to do a lot of identification and contacting owners with VPS/Dedicated options because they where hitting limits and lagging servers.