Lag for connected client in multiplayer

[Elyviere]

So me and a friend have been playing a death world together for a while now, and for the last few hours we've had a problem that's been getting worse and worse. The game is fine for the host, but the player who connects to him is getting significant lag (that essentially feels like frame drops, but yet fps shows as being 60.

Since my computer has better specs than his, we figured the best example would be with him hosting and me connecting (via LAN) and me lagging. The opposite would cause him to lag just the same, and if you need corresponding files for that too we can provide them.

The attached files are named as "My ___" and "His ___" so it's clear what is what. The attached file contains debug screenshots, logs and the save file (a zip inside a zip).