[rattray]

You may be interested in this technique, or some of the others in the article: https://www.citusdata.com/blog/2016/10/12/count-performance/...

EDIT: I'm also curious what version of Postgres you've experienced this on? Sounds like there may have been improvements to COUNT (DISTINCT in v11+

[caioariede]

If you're not making a lot of writes, that may be good approach since AFAIK the counts will only be updated after the table is ANALYZE'd