I once read on here that it’s counterproductive if too many people host their own farcaster hub. Why is that? Do hubs that run on slow machines clog the network?

yes 1) slow machines clog 
2) the number of hubs increases gossip traffic and more sync overhead

It's not inherently bad in anyway, just performance tests the hub implementation

Developer 🤓 build, develop and operate Farcaster solutions @ dtech.vision also love tech, decentralization, fitness and oldschool rap 😎

got it, thank you! Slowness and sync overhead make sense, but what is gossip traffic?

working on @microsub; creator of @degentipbot.eth; producer/dj; host of /campfire 🎧 + /downshift ⚙️

interesting, thanks for taking the time to explain Samuel!

It is named after the fact that peers gossip to each other about which messages they have seen and use this information to maintain a message delivery network.

From: https://docs.libp2p.io/concepts/pubsub/overview/

PS screw me  cc @downshift.eth I should have already wrote the libp2p guide on sync