Summary:
When looking at a large file in Diffusion:
- disable highlighting if it's huge and show a note about why;
- pick up a few other optimizations.
Test Plan: Locally, this improves the main render of `__phutil_library_map__.php` from 3,200ms to 600ms for me, at the cost of syntax highlighting (we can eventually add view options and let users re-enable it).
Reviewers: chad
Reviewed By: chad
Differential Revision: https://secure.phabricator.com/D14959
91a01e5703