Metabase cloud queries run slow until resync schema

We're using the hosted metabase cloud (*.metabaseapp.com) with MySQL connections to AWS RDS instances.

After some period of time, I'll return to use Metabase and all of the queries take an incredibly long time - I'm not sure how long exactly as I tend to give up after many minutes.

I've found I can do a "Sync database schema now" and having done so, all the queries will then execute very quickly.

At a guess, it feels like I'm purging a cache or something similar? Does anyone have any understanding of this and how we can avoid it?

Hi @tomnewby
Try contacting support via email: https://store.metabase.com/support
There's no caches involved here, and with the way Metabase makes queries, then it should not make any difference if you sync.
Metabase can make queries with up to 15 connections to the warehouse by default. Only one of these connections are used for sync.
It sounds like there's a problem with establishing connections or something else is going on, but it's difficult to say without looking at the logs.