Detect bottleneck of server via psycopg2
If you have access to PostgreSQL superuser account, then you can run arbitrary OS commands on the server as the OS user who is running the postgres server.  For example:

create temp table top (x text);
copy top from program 'top -b -n1';
select x from top limit 25;


However, if you were intentionally not given direct shell access to this server, whoever is running the server could consider this a hostile action.  It would probably be better to ask whoever is in charge to set up some OS-level monitoring solution, or explain to you any existing ones.