Setting to reduce resource usage on shared hosting?

I have Nextcloud installed alongside a small website on shared hosting. It’s working perfectly well - except that when I use Nextcloud - only a few times each month - I get an email warning from the hosting provider that Nextclould has maxed out the RAM (I only have 786MB, but that’s more than Nextcloud’s recommended minimum of 512MB), and very occasionally the CPU limit too.

Is there a setting (accessible to me in a shared environment, or that I could ask the hosting provider to set) that I can use to turn down Nextcloud’s RAM usage?

I’m looking to reduce resources too.
I’m using 512MB RAM + Swap and if I start uploading files and update on other computer at same time it will consume all the RAM and eventually because unusable.

Any suggestions?