If it is an extension issue, you may want to create an issue in its github repo with reproduction steps, current & expected behaviour.
I think the issue is mostly with windows systems can anyone please confirm whether the pg_sys_process_info() take long time to execute on Linux or Mac systems also? Like in case of Windows it call Win32_Process.
If we somehow we able to execute this query seperately, I think we would probably resolve this issue as then it won't block others.
