The overhead when using correlator plug-ins is very small.

However, you do need to ensure that you do not block the correlator for a long period of time. For example, you do not want to use a plug-in for doing extensive, synchronous, time-consuming calculations.

If you need to perform a time-consuming operation, use asynchronous processing and use the Apama client SDK to write a separate process that does the computations. For example, the correlator might communicate with this external process by emitting ComputeRequest events on a particular channel and the process would respond by sending ComputeResult events.