I am running a large number of TCP SIP accounts (outbound registrations from yate to provider) and looking for ways to optimize. I believe the problem is too many threads.
On a 4-core server the CPU is saturated with 700 outbound TCP registrations, no calls.
On an 8-core server I can handle up to 1000 outbound TCP registrations.
When I was previously running a large number of jabber client registrations they were easily handled by a 1- or 2- core server, more than 1000 registrations per server.