add option to disable & discard comment votes

[poVoq]

Requirements

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• Is this a backend issue? Use the lemmy-ui repo for UI / frontend issues.
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Is your proposal related to a problem?

Increasingly small instances struggle with database i/o on cheap and older hardware due to the high amount of incoming federated vote activities.

Describe the solution you'd like.

Votes on comments (as opposed to votes on posts) add only little to most threads compared to chronological comment sorting, but still represent a significant database load.

If would be good if instance admins had the option to disable votes on comments and automatically discard all incoming federated comment votes to lessen the database load.

Describe alternatives you've considered.

Vote batching would also help, but requires significantly more development effort and likely additions to the ActivityPub specs.

Additional context

Somewhat related issue: #4086

[poVoq]

Also relevant for geografically distant instances it seems: https://reddthat.com/comment/8316861

[Nutomic]

Similar to #5016

[dessalines]

Might be a dupe of #4086 , where I propose that we either have options to block all federated votes (or have instance allowlist/blocklists for them).

That's specifically for federated votes tho, this seems to be All comment votes.

[poVoq]

I think from a UI perspective disabling all comment votes is less confusing. It would be an instance option similar to disabling down-votes.