Does there excist a tool where it is possible to test the performance of ones VPS? I reckon that the resources are shared - so eventhough I have 4 cores for my plan - it might not work as fast as 2 cores with another hosting provider or??
The speed will be not related with the hosting provider, but with other clients sites/applications hosted on the server. If the other applications are heavy then you could have some resource problems, but in general this should be not a issue.