Looks good! If it isn't binding and you can't reduce the weight. If it is a 2 way cylinder you might try a bigger air valve, so the air can leave the cylinder faster. If that doesn't work a larger cylinder. should help. If the drum is straight, you could mount caster on a cross, so it will go up and down freely. Which you probably already know all this. So just chalk it up to me thinking out loud.
I discovered the reason why the action was slower than I expected. The piece of ****e Harbor Freight Compressor I bought 2 years ago is leaking air. You get what you pay for.
I just scored a good deal on a 26 Gallon Husky compressor with 6 pneumatic tools included for $224. The thing is a beast.