Herokuでのページ表示を早くするには

HerokuでWebアプリを２つ運用しているのですが、どちらも表示速度が遅いです。
DynoはHobbyで、２〜３秒のページロード時間が発生した後にページが表示されるというような具合です。
もう一つ似たようなWebアプリをAWSで運用しており、こちらは爆速表示されるので、RailsではなくHerokuが問題なのかなと考えています。

また、スピードテストツール（https://developers.google.com/speed/pagespeed/insights/）
で確認したところ、２つのアプリで以下のようなアラートが出ており、ここが原因であるように思えます。

トップページにアクセスした際のログは以下のようになっています

2020-10-25T04:26:21.311446+00:00 app[web.1]: I, [2020-10-25T04:26:21.311359 #4] INFO -- : [3e63243e-5365-4f54-94bf-8d4f3e859556] Started GET "/" for 60.71.180.167 at 2020-10-25 04:26:21 +0000
2020-10-25T04:26:21.312059+00:00 app[web.1]: I, [2020-10-25T04:26:21.311995 #4] INFO -- : [3e63243e-5365-4f54-94bf-8d4f3e859556] Processing by ItemsController#index as HTML
2020-10-25T04:26:21.399764+00:00 app[web.1]: D, [2020-10-25T04:26:21.399662 #4] DEBUG -- : [3e63243e-5365-4f54-94bf-8d4f3e859556] (2.2ms) SET @@SESSION.sql_mode = CONCAT(CONCAT(@@sql_mode, ',STRICT_ALL_TABLES'), ',NO_AUTO_VALUE_ON_ZERO'), @@SESSION.sql_auto_is_null = 0, @@SESSION.wait_timeout = 2147483
2020-10-25T04:26:21.403055+00:00 app[web.1]: I, [2020-10-25T04:26:21.402976 #4] INFO -- : [3e63243e-5365-4f54-94bf-8d4f3e859556] Rendering items/index.html.erb within layouts/application
2020-10-25T04:26:21.465483+00:00 app[web.1]: D, [2020-10-25T04:26:21.465349 #4] DEBUG -- : [3e63243e-5365-4f54-94bf-8d4f3e859556] Item Load (61.8ms) SELECT items.* FROM items WHERE items.browse_node_id = '57239051' ORDER BY RAND() LIMIT 12
2020-10-25T04:26:21.467323+00:00 app[web.1]: I, [2020-10-25T04:26:21.467246 #4] INFO -- : [3e63243e-5365-4f54-94bf-8d4f3e859556] Rendered items/_slider.html.erb (Duration: 64.1ms | Allocations: 957)
2020-10-25T04:26:21.513578+00:00 app[web.1]: D, [2020-10-25T04:26:21.513449 #4] DEBUG -- : [3e63243e-5365-4f54-94bf-8d4f3e859556] Item Load (45.7ms) SELECT items.* FROM items WHERE items.browse_node_id = '3895791' ORDER BY RAND() LIMIT 12
2020-10-25T04:26:21.515555+00:00 app[web.1]: I, [2020-10-25T04:26:21.515472 #4] INFO -- : [3e63243e-5365-4f54-94bf-8d4f3e859556] Rendered items/_slider.html.erb (Duration: 48.0ms | Allocations: 960)
2020-10-25T04:26:21.561362+00:00 app[web.1]: D, [2020-10-25T04:26:21.561268 #4] DEBUG -- : [3e63243e-5365-4f54-94bf-8d4f3e859556] Item Load (45.2ms) SELECT items.* FROM items WHERE items.browse_node_id = '170563011' ORDER BY RAND() LIMIT 12
2020-10-25T04:26:21.563172+00:00 app[web.1]: I, [2020-10-25T04:26:21.563106 #4] INFO -- : [3e63243e-5365-4f54-94bf-8d4f3e859556] Rendered items/_slider.html.erb (Duration: 47.4ms | Allocations: 961)
2020-10-25T04:26:21.609373+00:00 app[web.1]: D, [2020-10-25T04:26:21.609286 #4] DEBUG -- : [3e63243e-5365-4f54-94bf-8d4f3e859556] Item Load (45.7ms) SELECT items.* FROM items WHERE items.browse_node_id = '3895771' ORDER BY RAND() LIMIT 12
2020-10-25T04:26:21.611331+00:00 app[web.1]: I, [2020-10-25T04:26:21.611264 #4] INFO -- : [3e63243e-5365-4f54-94bf-8d4f3e859556] Rendered items/_slider.html.erb (Duration: 48.0ms | Allocations: 962)
2020-10-25T04:26:21.657498+00:00 app[web.1]: D, [2020-10-25T04:26:21.657382 #4] DEBUG -- : [3e63243e-5365-4f54-94bf-8d4f3e859556] Item Load (45.6ms) SELECT items.* FROM items WHERE items.browse_node_id = '16428011' ORDER BY RAND() LIMIT 12
2020-10-25T04:26:21.659455+00:00 app[web.1]: I, [2020-10-25T04:26:21.659396 #4] INFO -- : [3e63243e-5365-4f54-94bf-8d4f3e859556] Rendered items/_slider.html.erb (Duration: 48.0ms | Allocations: 961)
2020-10-25T04:26:21.660547+00:00 app[web.1]: I, [2020-10-25T04:26:21.660465 #4] INFO -- : [3e63243e-5365-4f54-94bf-8d4f3e859556] Rendered items/index.html.erb within layouts/application (Duration: 257.4ms | Allocations: 5612)
2020-10-25T04:26:21.662574+00:00 app[web.1]: I, [2020-10-25T04:26:21.662508 #4] INFO -- : [3e63243e-5365-4f54-94bf-8d4f3e859556] Completed 200 OK in 350ms (Views: 15.7ms | ActiveRecord: 246.2ms | Allocations: 7598)
2020-10-25T04:26:21.671562+00:00 heroku[router]: at=info method=GET path="/" host=test.com request_id=3e63243e-5365-4f54-94bf-8d4f3e859556 fwd="60.71.180.167" dyno=web.1 connect=0ms service=360ms status=200 bytes=71137 protocol=https
2020-10-25T04:26:22.023515+00:00 heroku[router]: at=info method=GET path="/assets/application-965f1c728ae1b0c01f318fb2f7a20c40925ce5544587fdd63db42ef4e0743546.css" host=test.com request_id=65676d78-522d-46af-90a9-78ab6304bccd fwd="60.71.180.167" dyno=web.1 connect=0ms service=1ms status=200 bytes=2591 protocol=https
2020-10-25T04:26:22.048168+00:00 heroku[router]: at=info method=GET path="/packs/js/application-ef121607a9dd258c2c03.js" host=test.com request_id=7ff80875-955f-4fbf-b210-4b93fe2c0502 fwd="60.71.180.167" dyno=web.1 connect=0ms service=12ms status=200 bytes=550728 protocol=https
2020-10-25T04:26:22.256900+00:00 heroku[router]: at=info method=GET path="/packs/css/application-09e9ac12.css" host=test.com request_id=6a786655-3715-4f72-99e8-224a6b0b79d6 fwd="60.71.180.167" dyno=web.1 connect=0ms service=2ms status=200 bytes=23243 protocol=https
2020-10-25T04:26:22.615186+00:00 heroku[router]: at=info method=GET path="/assets/ex-06e579a9698c64752b4fb57f2fe99cf49b4dd2f21c430e2cac110b6787de4778.png" host=test.com request_id=117840a6-a438-4b0e-93da-f8356e1d1469 fwd="60.71.180.167" dyno=web.1 connect=0ms service=1ms status=200 bytes=1582 protocol=https
2020-10-25T04:26:25.864501+00:00 heroku[router]: at=info method=GET path="/favicon.ico" host=test.com request_id=9de8b6fb-f56f-4301-87c2-f6cb8be8f72d fwd="60.71.180.167" dyno=web.1 connect=0ms service=1ms status=200 bytes=207 protocol=https