The SARS_ACTS table currently has 37,115,515 rows

I re-added the index on algorithm: idx_sars_acts_run_algorithm ON SARS_ACTS_RUN (algorithm)

serverdb=# explain analyze select count(*) as y0_ from SARS_ACTS this_ inner join SARS_ACTS_RUN tr1_ on this_.SARS_RUN_ID=tr1_.ID where tr1_.ALGORITHM='SMAT';
                                                    QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------
Aggregate  (cost=3983424.05..3983424.06 rows=1 width=0) (actual time=1358298.003..1358298.004 rows=1 loops=1)
  -> Hash Join  (cost=44.93..3983415.81 rows=3297 width=0) (actual time=2593.768..1358041.205 rows 1481710 loops=1)
       Hash Cond:  (this_.SARS_RUN_ID=tr1_.ID)
       ->  Seq Scan om sars_acts this_  (cost=0.00..3844241.84 rows=37092284 width=8) (actual time=0.026..1348954.763 rows=37461345 loops=1)
       ->  Hash  (cost=37.68..37.68 rows=580 width=8) (actual time=435.655..435.655 rows=441 loops=1)
             Buckets: 1024 Batches: 1 Memory Usage: 18kB
              -> Index Scan using idx_mars_track_run_algorithm on SARS_ACTS_RUN tr1_  (cost=0.00..37.68 rows=580 width=8) (actual time=10.580..435.273 rows 441 loops=1)
                   Index Cond:  ((algorithm)::text = 'SMAT'::text)

Total runtime: 1358298.664 ms <- 22.6383 minutes

(9 rows)