Yeah, weight’s a big part of it. Keep the frame light, use a carbon fork if you can, and ditch heavy racks or cargo packs unless you really need them. A lower seat and a good wheelbase will keep the bike from flipping on rocks, but don’t forget to keep the tire pressure right for the surface. If you’re pushing it hard, a lighter, narrower tire with a bit more grip can make a huge difference, just don’t overinflate or you’ll lose traction. The trick is to stay in the sweet spot between light enough to ride fast and heavy enough to stay planted when you hit a bump.