Web performance issues with external storage and Nextcloud 16

I have installed two instances of Nextcloud version on the same machine. One with local storage, and the other one with primary external storage (using object storage).

Both instances are handled with nginx, using the same configuration. I have enabled both APCu local memory cache, and redis for file locking.

However, I have completely different web rendering performances on the two instances. The requests (e.g. /login, or /settings/user) take up to 10 times longer on my NC instance with external storage enabled.

Using the nextwork tracking from Firefox I get 226ms for getting the /settings/users request on my NC1 instance (with local storage), and 1803ms on my other instance NC2 with external storage enabled.

After hours of investigations, I am running out of ideas why this big difference of web requests is happening. The web experience of NC2 is not acceptable.

Does anybody else have experience such problems? Would be great to get some hints.