Continuation of http://forum.arduino.cc/index.php?topic=335733.0 focusing on math optimizations.
[quote author=Coding Badly link=msg=2315254 date=1436838848] f1 = f1 * 1.10; f1 is float. 6.099 µs.
l1 = l1 / 10; l1 is long. 37.665 µs.
s1 = s1 / 10; s1 is short. 13.771 µs.
Tested on an Uno R3. Times adjusted for one load and one store.
Heed @MorganS's advice. And, don't "optimize" unless you know where the problem actually lies.
There's a guy called AddOhms with a channel on Youtube. He's got a song named "Post Your Code". hint. hint.