Comment 5 for bug 544496

(In reply to comment #4)
> I made a local branch in git off of the vline commit, reverted it in the
> branch, and merged master onto the branch. Performance is restored, plus
> everything seems a little bit faster than before! (Maybe Pauli's stuff causing
> that? Or maybe hallucinating....)
>

His changes only affect Xv.

> From what I understand about vline, it's something I want. Is the performance
> hit something that an app (like 'torcs') could find a workaround for, or is the
> hit unavoidable?

It avoids tearing on GL buffers swaps by waiting until the scanout is past the part of the screen being updated.