are subqueries cached? or only the final results

It really depends on the case . By default subqueries are not cached but some might require materialization (e.g. hashed part of hash join, order by + limit ) .

yes so I saw that in my case the first query takes 1 second and the next query takes 50ms, so the subquery is cached

Query metadata is cached but result is not . What you've observed is likely cold vs hot data performance.

oh no.. what does it mean? as well during runtime the first query is timed out but the ones after are not

Even though it times out first query could simply prime the data in OS page cache .

it says much

i.q.c.p.PGConnectionContext query cache used [fd=34248]

query cache only stores query plans, not the data or result .

:[ Bolek I dont want to bother you, maybe you can point me to some documentation on this?

I don't think query cache is documented apart from pg.cache. and http.query.cache.* references on https://questdb.io/docs/reference/configuration/ .