Moritz,
How would I know that it is alright to run more than one instance of Tor? Is it possible to prevent cpu use from causing VPS businesses threatening suspension?
Robert
First of all, if you don't limit your relay bandwidth and hit CPU limits, this will have a negative impact for Tor users. So you should always make sure that CPU (single core!) usage stays well below 100%. An indicator of a CPU-bound problem are log entries like
"Failed to hand off onionskin. Closing. Your computer is too slow to handle this many circuit creation requests!"
Judging from Atlas, your relay might have just gotten the Stable flag. For details, see https://blog.torproject.org/blog/lifecycle-of-a-new-relay