R1:9ab1b5a22db6

Make mundane performance improvements to Diffusion browse views

Summary:
Ref T2450. This reorganizes code to improve performance.

Mostly, there are a lot of things which are unique per commit (author name, links, short name, etc), but we were rendering them for every line.

This often meant we'd render the same author's name thousands of times. This is slower than rendering it only once.

In 99% of interfaces this doesn't matter, but blame is weird and it's significant on big files.

Test Plan:
Locally…