Considering a machine that handles 100 SIP concurrent calls (alaw) on asterisk 1.4, keeping the same configurations but going through asterisk 1.6 - 1.8, 10 - 11 - 13, will enhance the performance or not?
Was asterisk having a better throughput through versions? Which version is a big performance relevant on SIP technology?
I doubt anyone will really know. It will depend on your exact use of features of SIP and the PABX.
My guess is that performance will generally drift downwards as more features are added and more real time synchronisation bugs are plugged.
There is likely to be a large change between chan_sip and pjsip, but in which direction I don’t know. The new bridging architecture is likely to have made an impact, but only if you are not using external, direct media, bridges.