Yellow Boost 30 gems 2hr
Assume speed up 6x per minute (once each ten seconds, can go faster of course)
6x per min X 120min is 720
720 x 30 LB points is 21600 LB points
720 x 4gems is 2880 gems total
2880 + 30 = 2910
So in 2hrs, 21600 LB points with payout of 2910 gems
Thx for info. U r right, it's expensive lol