Вот и пруфы подъехали. Незначительные расхождения по времени. Стоит заметить что таблицы в базе довольно объёмные.

select
  l.status,
  array_agg(r.route_name) 
from routes r
join route_nodes rn on r.route_id = rn.route_id
join locations l on l.location_id = rn.location_id
where r.status = 34
group by l.status

Planning Time: 1.261 ms Execution Time: 1080.905 ms Timing: Generation 8.179 ms, Inlining 0.000 ms, Optimization 2.892 ms, Emission 39.771 ms, Total 50.842 ms

select
  l.status,
  array_agg(r.route_name) 
from routes r, route_nodes rn, locations l
where 1=1
  and r.status = 34
  and r.route_id = rn.route_id 
  and l.location_id = rn.location_id
group by l.status 

Planning Time: 1.707 ms Execution Time: 1024.166 ms Timing: Generation 8.284 ms, Inlining 0.000 ms, Optimization 3.059 ms, Emission 40.106 ms, Total 51.448 ms