Off by default.
If on, post-processing of queries is allowed when needed after an
index lookup, e.g. to resolve unindexable terms like REX
expressions, or only partially indexable terms.
If off, some queries are faster, but they may not be as
accurate if they aren't completely resolved. The error message
"Query would require post-processing" may be generated by
such queries if this is off.
Note that while enabling post-processing can improve the results of
queries where it is needed, it also takes more time and machine
resources (though generally not as much as a full linear search).
Thus careful thought should be given when considering enabling it,
especially with large (e.g. 100,000+ document) profiles.