Normally Jita (solar system) reaches a maximum of about 800-900 pilots on any given Sunday. On the Friday following the deployment of StacklessIO, 19 September, there were close to 1,000 concurrent pilots in Jita and on the Saturday, 20 September, the maximum number reached 1,400. This is more than have ever been in Jita at the same time. Under our old network technology Jita could become rather unresponsive at 800-900 pilots but on the Sunday, 21 September, it was quite playable and very responsive with 800 pilots, thanks to StacklessIO.
All that's running on Stackless Python.