General optimizations and Server-Side performance improvements.

Server and Client performance in general and especially since 1.13 has been steadily degrading due to the new features being added, so i suggest that as a way to recover from the community's demands and the current controversy, you work on improving overall server and client performance.

Client side mods such as Sodium, Phosphor, FerriteCore, and others prove that optimization is possible and can drastically improve performance for lower-end computers. This can drastically improve frame rates and optimize memory usage. Recent changes such as multithreaded chunk loading have helped with this, although it is far from perfect. Just taking some time to refactor the code for better performance can definitely draw more people to Java.

Server performance has also taken a huge hit since 1.13, some optimization and especially multithreading can go a long way for allowing servers to get above the 200 player threshold in a single world without huge TPS drops.

I'm not an experienced java developer (yet), but improving performance shouldn't take much longer then a usual content update. Players wont mind if they dont get new content if it means they can play Minecraft on lower end computers and not have to rely on mods to improve performance, along with servers being larger and able to host more people at once.