Benchmarks for guregu/null v4

benchmarks.txt

# Benchmarks for v4
BenchmarkIntUnmarshalJSON-8          	 4329932	       268 ns/op	     184 B/op	       2 allocs/op
BenchmarkIntStringUnmarshalJSON-8    	 4859449	       248 ns/op	     184 B/op	       2 allocs/op
BenchmarkNullIntUnmarshalJSON-8      	183305532	         6.46 ns/op	       0 B/op	       0 allocs/op
BenchmarkStringUnmarshalJSON-8       	 4850442	       241 ns/op	     181 B/op	       2 allocs/op
BenchmarkNullStringUnmarshalJSON-8   	184386210	         6.46 ns/op	       0 B/op	       0 allocs/op

# Benchmarks for v3
BenchmarkIntUnmarshalJSON-8          	 1756759	       682 ns/op	     392 B/op	       6 allocs/op
BenchmarkIntStringUnmarshalJSON-8    	 3163022	       380 ns/op	     216 B/op	       4 allocs/op
BenchmarkNullIntUnmarshalJSON-8      	 4112721	       304 ns/op	     208 B/op	       3 allocs/op
BenchmarkStringUnmarshalJSON-8       	 3140743	       375 ns/op	     213 B/op	       4 allocs/op
BenchmarkNullStringUnmarshalJSON-8   	 4092921	       296 ns/op	     208 B/op	       3 allocs/op

# Ran on a 2013 Macbook Pro.