Is there any Record for Maximum Concurrent Online Users In ELGG?

hi to all elgg lovers

i think there is a problem with performance of elgg,i want to know if any body test it in real project?

 have these questions:

how many online users does it support?

how many concurrent users does it support?

i read some where here that elgg has some problem with larg scale communities?

does any body test it ? please let me know .give me some statistics

best wishes

(how can we solve the performance issues)

best wishessssssssssssssssssssss