Performance impact of Boolean search

The performance of Boolean search is a function of the number of records associated with each term in the query, and also the number of terms and operators in the query.

As the number of records increases, and as the number of terms and operators increase, queries become more expensive.

The performance of proximity searches is as follows:

Searches using the proximity operators are slower than searches using the other Boolean operators.
Proximity searches that operate on phrases are slower than other proximity searches and slower than normal phrase searches.
Searches using the NEAR operator are about twice as slow as searches using the ONEAR operator, because word positioning must be calculated forwards and backwards from the target term.