[xdebug-general] slow codecoverage

When using xdebug_start_code_coverage with the option XDEBUG_CC_UNUSED
the script runs much slower than without this option. Almost 50%.

Is there a possibility to optimize this?

The reason I want this to be faster is because I'm trying to use it to
see what parts of my application code is actually used when the testers
has completed their system test. But it slows the application down so
much that I don't know if I can use it.

/Are P.