PostgreSQL loads the processor up to 100%, who faced it?

Question

PostgreSQL

There was such a problem, the request select this_.id as y0_ from vacancies this_ where this_.company_id=$1 limit $2 loads the processor by 100%, it is executed by hand with a bang and very fast, the server configuration is sufficient, for a base of 6GB - 16GB of RAM, 6 cores . Changing and tuning the config does not help. "Limit" costs 1000.
Already hands down, and everything was fine, worked well, and then bang and that's it, loading 100%. The service is written in Java.

Answer 1

Is there an index on the company_id field?