Subarist of course we will continue to refine and improve core, it's bundled extensions, and the FoF extensions. Some candidates for improvement are already underway.
The bigger part of the puzzle however, are 3rd party extensions. With the new architecture in 2.x, slowdowns can and do happen much easier than they used to. I've already identified multiple examples of this, but please understand it is down to 3rd party extension authors to optimise their code going forward.
Regarding the "rhythm" of Flarum - this is expected, it's a new major version using different underlying architecture and techniques. If it had the same as 1.x, then I'd be worried.
We will always look at reports of slowdowns, etc, but we need details (extensions installed, relevant settings, server config and so on), a "it's slower" or "it's different" does not help us to improve.
One last point, although the communities are recognised by the Flarum Foundation, please remember that in no way are they under our control or influence. We don't have any visibility on their configuration, settings or similar.