- 10,000,000 documents in the index;
- 5-10 terms per document;
- 200,000 unique terms for a tokenized field.
Obviously calculating sizes of 200,000 intersections with FilterCache is 100 times slower than traversing 10 - 20,000 documents for smaller DocSets and counting frequencies of Terms.
Not applicable if size of DocSet is close to total number of unique tokens (200,000 in our scenario).