How to diagnose TruClient-Vusers stopped during initialization?

(LR 12.53 Patch 2 / TruClient (FF) / Win 7 SP1)

I'm trying to test the scalability of a new LR load generator (20 cores, 96GB memory) with a scenario running a single FF TC script with 200 Vusers (load generators Vuser initialization quota set to 1):



While running this scenario the initialization of Vusers always stops after 82 Vusers and then the controller reports a timeout for the rest of the Vusers (the load generator has plenty of unused cpus and memory left despite of running 82 idle Firefox instances):



Now I'm wondering how to diagnose this issue?

Are there any limitations (other than memory and cpu) on the maximum number of TC Vusers supported by a single load generator?

Cheers,

Thomas