How to do many updates in a single query WAY faster

gistfile1.sql

UPDATE counties_results o SET pres_dem_pct = n.pres_dem_pct, pres_gop_pct = n.pres_gop_pct,
  pres_oth_pct = n.pres_oth_pct, pres_pctrpt = n.pres_pctrpt
FROM ( VALUES
(48.51, 39.69, 11.8, 100, 'AK', '02000'),
(51.65, 41.67, 6.68, 100 , 'AL' , '01001' ),
(52.14, 42.4, 5.46, 100 , 'AL' , '01003' ),
(51.94, 42.24, 5.82, 100 , 'AL' , '01005' ),
(60.28, 34.95, 4.76, 100 , 'AL' , '01007' ),
(53.19, 42.04, 4.77, 100 , 'AL' , '01009' ),
(45.07, 50.85, 4.08, 100 , 'AL' , '01011' ),
(45.78, 49.06, 5.16, 100 , 'AL' , '01013' ),
(57.94, 36.59, 5.47, 100 , 'AL' , '01015' ),
(46.98, 48.19, 4.83, 100 , 'AL' , '01017' ),
(57.38, 37.44, 5.18, 100 , 'AL' , '01019' ),
(51.15, 43.66, 5.19, 100 , 'AL' , '01021' ),
(48.13, 47.03, 4.84, 100 , 'AL' , '01023' ),
(54.74, 40.23, 5.03, 100 , 'AL' , '01025' ),
(48.85, 45.55, 5.59, 100 , 'AL' , '01027' ),
(43.34, 52.17, 4.5, 100 , 'AL' , '01029' ),
(54.65, 40.71, 4.64, 100 , 'AL' , '01031' ),
(53.65, 41.07, 5.28, 100 , 'AL' , '01033' ),
(57.72, 36.74, 5.55, 100 , 'AL' , '01035' ),
(44.02, 52.32, 3.66, 100 , 'AL' , '01037' ),
(57.02, 38.25, 4.74, 100 , 'AL' , '01039' )

) AS n(pres_dem_pct, pres_gop_pct, pres_oth_pct, pres_pctrpt, st_usps, fips)
 WHERE o.st_usps = n.st_usps AND o.fips = n.fips;