rspec/rspec-support — pull request #140 by myronmarston (2014-12-24 21:03:57+00:00)
Title: Optimize `RSpec::CallerFilter`.

- Use `caller_locations` rather than `caller`. It's apparently
much faster. I suspect that it's due to the fact that `caller`
has to due some extra calculation for each stack frame in order
to combine them into a full line description string, where as
`caller_locations` returns an object with the separate stack
frame attributes and does the full line description calculation
when you call `to_s`.
- Immediately return when we have the line, rather than updating `i`
and `increment` for now reason.

/cc @xaviershay