The FastMath utility often gives better performance than Java's standard Math class. These are the results of a benchmark on my PC of StrictMath, FastMath, and Math.
Name StrictMath FastMath Math Runs=10000000 Java 1.8.0_131 (1.8.0_131-b11) Java HotSpot(TM) Client VM (25.131-b11)
abs 4 1.0 13 3.1702 4 1.0171
acos 58 1.0 145 2.5009 57 0.9924
asin 55 1.0 115 2.0705 55 0.9955
atan 84 1.0 68 0.8105 84 1.0007
atan2 101 1.0 108 1.0697 100 0.9917
cbrt 121 1.0 95 0.7920 119 0.9898
cos 95 1.0 53 0.5573 73 0.7737
cosh 113 1.0 48 0.4292 113 0.9971
exp 91 1.0 33 0.3717 76 0.8419
expm1 104 1.0 43 0.4113 103 0.9916
hypot 100 1.0 108 1.0786 100 0.9997
log 82 1.0 72 0.8818 38 0.4740
log10 112 1.0 143 1.2806 38 0.3448
log1p 92 1.0 144 1.5593 92 0.9971
pow 258 1.0 184 0.7138 105 0.4074
sin 95 1.0 54 0.5717 77 0.8137
sinh 132 1.0 49 0.3723 128 0.9688
sqrt 12 1.0 12 0.9929 12 0.9934
tan 131 1.0 78 0.5965 110 0.8391
tanh 79 1.0 34 0.4302 79 0.9995
The integer number is the number of nanoseconds per operation (smaller is better) and the float number is the percentage of the time of the StrictMath class (smaller is better, < 1 is faster than StrictMath). As you can see, the exp() function is 2.3x faster in the FastMath class than standard.