Simply grab the ISO and see yourself. I for one did experience horribly
slowdowns in the three various maps I tried with two bots.
The original Xonotic scales very well and is know to work well on older
systems. The ChaosEsque mod seems a lot different here to me. It adds lots of
new models where a few have a pretty high poly count and enhanced physical
calculations that seem to bog down the engine.
I experienced this some versions before and this still has not really
changed.
Since it runs much faster on other systems (like on Youtube) of course this
could possibly be an issue with the system I used for testing but other much
more demanding games run fine (as I pointed out).