Even though there is no enforced limitation on how many servers or slots you can run in a single instance, we do not recommend running more than 200 virtual servers or 2000 slots (whichever comes first) per TeamSpeak instance for performance and stability reasons. We also recommend not using more than 1000 slots per virtual server.
The reason this recommendation is not enforced is that this is a very conservative recommendation and we recognize that from an administrative point of view it is easier managing a single instance as opposed to multiple ones. We are also aware of hosters that exceed these recommendations and still provide a safe and stable service, however in order to do so you need to have good knowledge of your system and tweak things in multiple locations, which can be an extremely time consuming process.
Exceeding the recommendation is not recommended and since it becomes increasingly harder to debug and pinpoint possible problems, we cannot and won't provide support if you exceed the recommendations outlined above.