Recently decided to have a go at mapping, learned the bare basics of hammer, and threw together a simple map. When I played it in-game, there is this irritating problem - jumping is laggy, climbing or descending ramps leads to the view passing through them and into black space or levitating mid air. The levitating player view behaves as if you were where you should be; bumping into walls and picking up health packs. Firing even hits as if you were where you should be on the ground. Firing weapons, reloading, or taunting places the view point wehre you be - and constantly firing or reloading while moving fixes the problem. I'm sure this is a stupid mistake or I've missed something important in the tutorials, but can't find what it is.