It improves rasterization and upload times by a lot in almost all of the test cases I can find. The only drawback is that our invalidation granulatiry is the tile so invalidation gets coarser as we increase the tile size.
512 is a bit special because it is the limit above which a different texture upload path is taken, so there will be more risk of performance side effects if/when we decide to make tiles even larger.
Differential Revision: https://phabricator.services.mozilla.com/D155822
403b0c1b58