Xdebug on Tool Labs is slowing down web requests, and cannot be disabled without installing a complete other web server for a specific tool and running it on webgrid-generic.
As I mentioned on IRC:
- Have you measured that it's xdebug that causes the slowdown?
- you can override php.ini using .user.ini
- you can override the full lighttpd configuration if that is insufficient
See https://wikitech.wikimedia.org/wiki/Help:Tool_Labs/Web for more details.
FWIW I think it's well known that xdebug does slow down requests and isn't intended for production environments (e.g. https://getcomposer.org/doc/articles/troubleshooting.md#xdebug-impact-on-composer)
I discovered that NFS was a huge slowdown of all webservices, and that running a webservice in /tmp, I copied the files to the bastion /tmp and made a symlink, and it worked (strangely, lighttpd could access the bastion's /tmp, because there wasn't anything in the webserver host's /tmp when I checked).
Although NFS did slow down the webservice hugely, other factors (like xdebug) are still affecting the webservice. I'm going to assign myself this task and do some more testing to find out whether xdebug (and maybe other factors) make a difference in the speed of the webservice.