How many things can one instance of Thingworx handle?

Hi,

I've been trying to set up some kind of performance tests, on a Thingworx 7.0 instance.

These are the machine specs:

    OS: Ubuntu 14.04.4 LTS

    DB: PostgreSQL 9.4.7

    App Server: Apache Tomcat/8.0.24 (16 GB dedicated memory)

    Hardware:

              RAM: 28GB

              CPU: Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz (QuadCore)

But it seems that I can only connect ~3914 things at once, but the documentation states that one Thingworx instance supports up to 50000 connected things.

I've also tried to use ConnectionServers, and again per server, the number of connected things seems to be limited (only ~3974).

Is there any extra configuration, either for Twx or for OS that I'm not aware of?

Any help would be much appreciated

Leo