PPI::XS provides XS-based acceleration of the core PPI packages. It
selectively replaces a (small but growing) number of methods throughout
PPI with identical but much faster C versions.
Once installed, it will be auto-detected and loaded in by PPI completely
Because the C implementations are linked to the perl versions of the
same function, it is preferable to upgrade PPI::XS any time you do a
major upgrade of PPI itself.
If the two fall out of sync, the integration between the two is designed
to degrade gracefully. PPI::XS is capable of determining which functions
are no longer equal, and will simple leave the perl version alone,
deleting the C version to free up the memory.
If the versions of the two get so far apart that they become completely
incompatible, PPI::XS will simply silently not load at all.
Beyond that, there isnt that much more you really need to know. :)