It's nothing. You don't recompute everything for each page refresh. Your sucks well the data, compute reputation total over time and discard old raw data when your local cache is full.

Historical daily data gets packaged, compressed, and cross signed by multiple high reputation entities.

When there are doubts about a user's history, your client drills down those historical packages and reconstitute their history to recalculate their reputation

Whenever a client does that work, they publish the result and sign it with their private keys and that becomes a web of trust data point for the entire network.

Only clients and the network matter, servers are just untrustworthy temporary caches.

Any solution that only works because the platform is small and that doesn't scale is a bad solution though.