I did ski-touring in the past with a small backpack (10 kg); it was fun. I have recently done a short ski tour with a heavy backpack (20 kg, including camping gear); it was pretty much pure suffering on the way down. I was falling all the time - I couldn't do turns on any significant downhill slope, so had to look for alternative paths, where you don't need to turn so much. I would rather walk downhill, but I was hoping that somehow I'd finally "figure it out"; it didn't happen.
Is there any specific technique I should employ for such downhill skiing? Or maybe specific equipment?