そういえば高いHeroku Postgresは診断書を書いてくれるよ！
$ heroku pg:diagnose -a zundan-mastodon
RED: Hit Rate
Name Ratio
────────────────────── ──────────────────
overall cache hit rate 0.9512841897336148
YELLOW: Indexes
Reason Index Index_scan_pct Scans_per_write Index_size Table_size
────────────────────── ────────────────────────────────────────────────────── ────────────── ─────────────── ────────── ──────────
Low Scans, High Writes statuses::index_statuses_on_reblog_of_id_and_account_id 9.53 0.04 106 MB 1183 MB
: