Remove stamp in favor of plain old strftime calls
The stamp gem is super cool and convenient but has some overhead:
Iterations: 500,000
stamp ------------------------------------------------------------------
{"2.1.7":{"gc":"disabled","time":2.53,"gc_count":0,"memory":"457 MB"}}
strftime ---------------------------------------------------------------
{"2.1.7":{"gc":"disabled","time":0.91,"gc_count":0,"memory":"251 MB"}}
(source: https://gist.github.com/tsigo/e1a63074d2279cbd60f4)
We don't actually use stamp in very many places - certainly nothing that's called 500,000 times - but one critical place is in the projects/commits/_commits.html.haml
partial that does get iterated. It's also used in the time_ago_with_tooltip
helper which we know gets called a lot. We'd probably see some savings there by replacing these calls with basic strftime
calls.