Very slow /unread endpoint call when switching channels

@luca-nardelli / @tomz - I have another setting which I would like to run by you all.

Can you also check if ServiceSettings.EnableLinkPreviews is set to true and if so, set it to false and see if that helps?

EDIT: To clarify, set both ServiceSettings.EnableLinkPreviews and ServiceSettings.EnablePermalinkPreviews to false.

Thanks.