I’ve finished further testing and can confirm the issue is not related to R2. The same behavior (slow-loading avatars on posts and when clicking on a username) persists even with a properly configured AWS S3. It is also not a firewall issue, as “ufw status” confirms that the firewall is currently disabled. I plan to conduct more tests this weekend in a staging environment, where I can keep the forum running for longer periods and take it offline if necessary without any issues.