Title really covers it, but in long form:
There was a noticeable improvement in the responsiveness and stability of the Jita nodes. Despite having 2 full fleets active in the system at one point at no point did the system crash nor were lag spikes responsible for any of our errors during the weekend.
From my own perspective I was able to perform the large amounts of ship moving and trading shenanigans that caused so many problems last year without significant issue. The now game enforces a limit on the number of fitted ships you can trade/fly between hangers which is probably part of the reason.
So, once again thank you to the many people at CCP whose iterative improvements in the background systems made all our lives better this year. Your work goes far too unappreciated but due to it we were able to have an event attended by 1700 unique people over the weekend with a max pilot involvement of ~550, in the busiest system in the game, without a single serious problem of any kind.