I am using Kaminari to paginate two sets of data on a page in my app. One set of data has around 620 records and the other around 150. So not many compared to some.
However, the pagination partials are taking around 900ms to load for each. See: 21:46:38 rails.1 | Rendered items/_paginator.erb (952.8ms)
Apparently this is due to a COUNT that Kaminari is doing. More details here: https://github.com/amatsuda/kaminari/issues/545
I have looked around, even here on SO and found similar questions and loads of answers on how to speed up COUNT but nothing in relation to speeding it up in tandem with Kaminari.
Any ideas on how to do this?
My terminal output for this request:
22:46:31 rails.1 | (1.6ms) SELECT COUNT(*) FROM "coasters" WHERE "coasters"."superseded_at" IS NULL AND (material = 'steel')
22:46:31 rails.1 | (0.7ms) SELECT COUNT(*) FROM "coasters" WHERE "coasters"."superseded_at" IS NULL AND (material = 'wood')
22:46:31 rails.1 | Rendered shared/_breadcrumb_text.html.erb (9.6ms)
22:46:31 rails.1 | Rendered shared/_fact_bar.html.erb (0.3ms)
22:46:32 rails.1 | ParkChain Load (0.7ms) SELECT "park_chains".* FROM "park_chains"
22:46:32 rails.1 | Rendered theme_parks/parks/_filter_links.html.erb (11.5ms)
22:46:32 rails.1 | Rendered theme_parks/coasters/_filter_links.html.erb (3.2ms)
22:46:33 rails.1 | (0.4ms) SELECT COUNT(*) FROM "parks"
22:46:33 rails.1 | Rendered theme_parks/parks/_park_paginator.erb (1029.5ms)
22:46:33 rails.1 | Park Load (1.2ms) SELECT "parks".* FROM "parks" ORDER BY name ASC LIMIT 25 OFFSET 0
22:46:33 rails.1 | Rendered theme_parks/parks/_park.html.erb (7.9ms)
22:46:33 rails.1 | Rendered theme_parks/parks/_park_grid.html.erb (175.6ms)
22:46:34 rails.1 | Rendered theme_parks/parks/_park_paginator.erb (961.1ms)
22:46:36 rails.1 | (1.7ms) SELECT COUNT(DISTINCT "coasters"."id") FROM "coasters" LEFT OUTER JOIN "parks" ON "parks"."id" = "coasters"."park_id" LEFT OUTER JOIN "cycles" ON "cycles"."coaster_id" = "coasters"."id" WHERE "coasters"."superseded_at" IS NULL
22:46:36 rails.1 | Rendered theme_parks/coasters/_coaster_paginator.erb (1104.5ms)
22:46:36 rails.1 | SQL (2.6ms) SELECT DISTINCT "coasters"."id", parks.name AS alias_0, coasters.name AS alias_1 FROM "coasters" LEFT OUTER JOIN "parks" ON "parks"."id" = "coasters"."park_id" LEFT OUTER JOIN "cycles" ON "cycles"."coaster_id" = "coasters"."id" WHERE "coasters"."superseded_at" IS NULL ORDER BY parks.name ASC, coasters.name ASC LIMIT 25 OFFSET 0
22:46:36 rails.1 | SQL (16.8ms) SELECT "coasters"."id" AS t0_r0, "coasters"."name" AS t0_r1, "coasters"."inversions" AS t0_r2, "coasters"."material" AS t0_r3, "coasters"."notes" AS t0_r4, "coasters"."lat" AS t0_r5, "coasters"."lng" AS t0_r6, "coasters"."manufacturer_id" AS t0_r7, "coasters"."park_id" AS t0_r8, "coasters"."created_at" AS t0_r9, "coasters"."updated_at" AS t0_r10, "coasters"."slug" AS t0_r11, "coasters"."covering" AS t0_r12, "coasters"."style" AS t0_r13, "coasters"."model" AS t0_r14, "coasters"."layout" AS t0_r15, "coasters"."order_ridden" AS t0_r16, "coasters"."dates_ridden" AS t0_r17, "coasters"."on_ride_photo" AS t0_r18, "coasters"."powered" AS t0_r19, "coasters"."length" AS t0_r20, "coasters"."height" AS t0_r21, "coasters"."speed" AS t0_r22, "coasters"."coaster_sort" AS t0_r23, "coasters"."is_milestone" AS t0_r24, "coasters"."version_number" AS t0_r25, "coasters"."version_reason" AS t0_r26, "coasters"."version_ridden_after" AS t0_r27, "coasters"."position" AS t0_r28, "coasters"."relocated" AS t0_r29, "coasters"."renamed" AS t0_r30, "coasters"."rethemed" AS t0_r31, "coasters"."steel_10" AS t0_r32, "coasters"."wood_10" AS t0_r33, "coasters"."original_version_id" AS t0_r34, "coasters"."superseded_at" AS t0_r35, "parks"."id" AS t1_r0, "parks"."name" AS t1_r1, "parks"."location_1" AS t1_r2, "parks"."location_2" AS t1_r3, "parks"."location_3" AS t1_r4, "parks"."lat" AS t1_r5, "parks"."lng" AS t1_r6, "parks"."created_at" AS t1_r7, "parks"."updated_at" AS t1_r8, "parks"."location_4" AS t1_r9, "parks"."country" AS t1_r10, "parks"."park_chain_id" AS t1_r11, "parks"."notes" AS t1_r12, "parks"."visit_count" AS t1_r13, "parks"."dates_visited" AS t1_r14, "parks"."slug" AS t1_r15, "parks"."order_visited" AS t1_r16, "parks"."logo" AS t1_r17, "cycles"."id" AS t2_r0, "cycles"."coaster_id" AS t2_r1, "cycles"."notes" AS t2_r2, "cycles"."date" AS t2_r3, "cycles"."created_at" AS t2_r4, "cycles"."updated_at" AS t2_r5 FROM "coasters" LEFT OUTER JOIN "parks" ON "parks"."id" = "coasters"."park_id" LEFT OUTER JOIN "cycles" ON "cycles"."coaster_id" = "coasters"."id" WHERE "coasters"."superseded_at" IS NULL AND "coasters"."id" IN (21926, 22414, 21927, 21939, 21963, 21964, 21962, 21965, 21800, 21790, 21791, 21793, 21794, 21795, 22378, 21845, 21792, 21842, 21941, 22179, 22144, 22145, 22065, 22196, 22188) ORDER BY parks.name ASC, coasters.name ASC
22:46:36 rails.1 | Rendered theme_parks/coasters/_coaster.html.erb (273.5ms)
22:46:36 rails.1 | Rendered theme_parks/coasters/_coaster_grid.html.erb (576.9ms)
22:46:37 rails.1 | Rendered theme_parks/coasters/_coaster_paginator.erb (968.7ms)
22:46:37 rails.1 | Rendered theme_parks/index.html.erb within layouts/application (6285.8ms)
22:46:38 rails.1 | Rendered shared/_banner_slideshow.html.erb (0.1ms)
22:46:38 rails.1 | Rendered shared/_flash_messages.html.erb (0.2ms)
22:46:38 rails.1 | Completed 200 OK in 7547ms (Views: 7216.3ms | ActiveRecord: 33.3ms)
UPDATE: 
Views: 7216.3ms | ActiveRecord: 33.3ms: your database appears to have nothing to do with it, actual interaction with the database is less than 0.5% of the total render time. There is something else slowing down the process. You may need a profiler to find it. - D-side