enable-profiling (&optional (verbosep t))
Resets any existing profile samples and enables profiling for future XPath compilations.
Previously returned closures that were created with profiling disabled are not affected by this setting, but closures created during an earlier profiling session will start sampling again.
But note that evaluate, node-matches-p, and pattern-case will recompile their cached closure when this setting has changed.
Profiling is not thread safe.