> Significant backend server architecture changes rolled out. Twitter should feel faster.

Without more details, I'm going to hypothesize that these are just the sort of routine improvements and performance wins that such teams deploy on a semi-regular basis. Anything can be called a "significant architecture change" if you want it to be.

If it is in fact a very major change, though, it was probably in the pipeline long before Elon arrived, given the time it takes to develop and fully test such things. It's quite possible that the past couple months were spent entirely on testing and refining a large-scale change that had already been mostly complete pre-acquisition.