Hi, tantivy dev here.
There are two recent performance improvements in tantivy, which should make term aggregations considerable faster.
https://github.com/quickwit-oss/tantivy/pull/2740 https://github.com/quickwit-oss/tantivy/pull/2759
https://github.com/quickwit-oss/tantivy/pull/2740 https://github.com/quickwit-oss/tantivy/pull/2759