Depends on the requirements. Writing the code in a natural and readable way should be number one.
Then you benchmark and find out what actually takes time; and then optimize from there.
At least thats my approach when working with mostly functional languages. No need obsess over the performance of something thats ran only a dozen times per second.
I do hate over engineered abstractions though. But not for performance reasons.
Very nice! Loving the Explore tab for finding communities, and the animations feel good!
I have a feature request: dark mode thats more of a dark gray than "amoled black". I find the contrast of white text on pitch black too much.
Edit: ...and iPad support would be awesome!