Summary:
See PHI413. You can pre-generate these with `bin/people profileimage --all`, but they're needlessly expensive to generate.
Streamline the workflow and cache some of the cacheable parts to reduce the generation cost.
Test Plan:
- Ran `bin/people profileimage --all` and saw cost drop from {nav 15.801s > 4.839s}.
- Set `defaultProfileImagePHID` to `NULL` in `phabricator_user.user` and purged caches with `bin/cache purge --all`.
- Loaded user directory.
- Saw default images regenerate relatively quickly.
Differential Revision: https://secure.phabricator.com/D19168
14fe941c34