This issue is from Playerbot Repo but I don't think it is related to bot AI.
After updating the core since March 2017 the game became unplayable as the Random Movement Generator suddenly became so slow that it causes a massive lag even with a relatively small number of bots. In 2016 the server could run up to 1500 bots, but now even 100 is a huge problem. Maps, vmaps and mmaps were re-generated using the latest extractors. Bot AI does not use random movement generator.
Please see the attached screenshot (only 100 bots were active) - the Map::VisitNearbyCellsOf causes 60% of the CPU usage with no direct calls to Playerbot AI.
I think this is so because the bots are evenly spread across the enitre map leaving no cells without players so the update queue is always big.
I am testing this on Windows using my playerbot repo, but there are only minor core changes and I don't think the issue is related to playerbot code at all.
I can't figure out was changed recenly affecting the performance so heavily. Maybe someone here could give a hint?