The server-timing mechanism in Performance Lab is fantastic! However, it only seems to work with a standard/initial page request, and not any AJAX requests - which my site (buddypress-based) makes significant use of.

So, it would be great to be able to send Server-Timing headers for each ajax request to have a better understanding of how much server time is taken by each one.

I'd be more than happy to contribute to this effort if I can be pointed in the right direction - it seems like the server-timing mechanism doesn't get loaded at all for an ajax request.