The existing Sandbox profiles refer to various unsupported versions of macOS. These conditionals are evaluated at runtime, so have a non-zero cost, and are always false for anything shipped in the last few years.
Clean up these old entries!
Created attachment 294507 [details]
Committed r208611: <http://trac.webkit.org/changeset/208611>
This change is wrong. I misread the Scheme conditional clause as if it was C++, instead I should have recognized that Scheme's conditional looks like this:
(if (predicate ...)
(stuff to do if true)
(stuff to do if false))
I will fix this in Bug 165187.