>10K fields: is it a problem? Why exactly?

Elastic Stack Elasticsearch
1

Hello.
I have shards about 20G size with 600K docs each. Response time is acceptable.

After a shard receives about 200K updates, it ends up 20 segments, response time exceeds the reasonable value.

In profile, I spotted really high create_weight time (300 ms) for CombinedFieldQuery (7 fields, 3 terms - not much), although underneath TermQueries create weight and scorers quite fast.

May many fields cause high create_weight for CombinedFieldQuery?
What are other usual implications? Which metrics/stats to check when number of fields is hight?

2

I've tried to reproduce it locally: built an 45G index with 10K fields in mapping and 1M docs, having about 30 segments. I don't see slow create_weight there.
May you give a clue where to look at?