Hi Roman,
Starting with OptiSystem 10 we have supported multi-threading for paralleled systems and now in OptiSystem 13 we support multi-threaded parameter sweeps.
Here are some links to the two releases:
https://optiwave.com/resources/latest-news/optisystem-10-0-june-2011/
https://optiwave.com/resources/latest-news/new-version-optisystem-13-0/
Cheers!