Filter performance difference (Bool vs Terms)

I have a terms filter (over multiple fields) and an equivalent boolean query; but the terms query is faster. Is some optimization performed when the terms filter is applied (which thereby allows it to perform better than the equivalent boolean query)?

Yep :slight_smile: You can read more about it here:

Generally, filters are executed in a "non-scoring" mode which gives them two main performance advantages. Firstly, they can omit the actual scoring of the document. Scoring a doc is relatively quick (the summation of a bunch of multiplications), but even 1ns for a billion documents is 1 second of computation.

Secondly, non-scoring filters can be cached, meaning subsequent executions of the filter clause can leverage the cache instead of hitting the various data-structures.

Where possible, we encourage people to convert queries => filters for better performance (assuming you don't need the scoring aspect)