[Freeswitch-users] FS stress test issue

while i was doing stress test over FS, things look pretty good as FS is able to hold 800 concurrent calls with a call loss rate at around 0.1%, when leveling up to 1000 concurrent calls, the call loss soars to 10-20%, i made some modification to switch.conf like <param name="max-sessions" value="2000"/> <param name="sessions-per-second" value="100"/> but things didn't get any better, the host CPU usage rate is around 80-90%, memory usage: 10%, network load 10%, so i think there should be someway we can make FS handle more concurrent calls, any ideas?