A couple of weeks ago I moved to a new hosting provider (kyun), which is cheaper and better than my previous one, but seems to have much slower disks.
Response times have increased significantly, and that forced to me to review several query execution plans. In particular, featured collection is now generated much faster, and that may have an impact even if your hardware is good, because Mastodon instances tend to retrieve these collections when activities are delivered to them, making hundreds of requests at the same time.

https://mitra.social/objects/0195ca3c-14ee-6cce-2666-23c5a4e35fdc