Move your stance in so your feet sit under your hip sockets with your feet pointing slightly out. Grip the bar just outside your shins.
Don't start with your hips so low. You want your shins vertical at all times. For me, the best way to acheive this is dropping to the bar by pushing my butt back instead of bending over to grip it.
Don't spend so long at the bar before pulling. You want to minimise the time between gripping and pulling, even if you're pulling slack ouf of the bar.
Don't worry about descent speed at all - a long as you maintain control of the bar as it comes down you're fine.
My humble submission illustrating all bar the first point: