I've had discussions with @epriestley about this before, but I am opening this as a separate maniphest. Basically, `pygmentize` is super resource-intensive and we don't have many controls in place to prevent `pygmentize` from saturating available system resources. Currently, by opening a bunch of (approximately 10) large merge commits in separate tabs I am able to DOS our Phabricator install (subsequent requests will hit a `proc_open()` error) and saturate CPU usage on a `c1.xlarge` EC2 instance.