The performance improvement measured by jmh benchmark
http://cr.openjdk.java.net/~sherman/8172921/MyBenchmark.java

OLD: # Run complete. Total time: 00:04:05

Benchmark Mode Cnt Score Error Units
MyBenchmark.ZFS_Exists avgt 50 3.520 ± 0.421 ms/op
MyBenchmark.ZFS_ExistsNG avgt 50 48.415 ± 1.472 ms/op
MyBenchmark.ZFS_GetPath avgt 50 30.918 ± 17.053 ms/op
MyBenchmark.ZFS_GetPathExists avgt 50 30.283 ± 13.618 ms/op
MyBenchmark.ZFS_GetPathIsDirectory avgt 50 48.042 ± 17.760 ms/op
MyBenchmark.ZFS_GetPathIsRegularFile avgt 50 41.289 ± 16.551 ms/op
MyBenchmark.ZFS_GetPathNewInputStream avgt 50 66.140 ± 8.749 ms/op
MyBenchmark.ZFS_GetPathToRealPath avgt 50 30.339 ± 12.684 ms/op
MyBenchmark.ZFS_IsDirectory avgt 50 8.612 ± 0.564 ms/op
MyBenchmark.ZFS_IsRegularFile avgt 50 9.168 ± 0.599 ms/op
MyBenchmark.ZFS_Itr avgt 50 19.675 ± 0.399 ms/op
MyBenchmark.ZFS_ToRealPath avgt 50 4.038 ± 0.372 ms/op

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NEW: # Run complete. Total time: 00:03:54

Benchmark Mode Cnt Score Error Units
MyBenchmark.ZFS_Exists avgt 50 2.984 ± 0.183 ms/op
MyBenchmark.ZFS_ExistsNG avgt 50 46.770 ± 1.737 ms/op
MyBenchmark.ZFS_GetPath avgt 50 17.608 ± 0.637 ms/op
MyBenchmark.ZFS_GetPathExists avgt 50 26.461 ± 22.612 ms/op
MyBenchmark.ZFS_GetPathIsDirectory avgt 50 28.967 ± 16.656 ms/op
MyBenchmark.ZFS_GetPathIsRegularFile avgt 50 19.763 ± 0.616 ms/op
MyBenchmark.ZFS_GetPathNewInputStream avgt 50 35.818 ± 13.386 ms/op
MyBenchmark.ZFS_GetPathToRealPath avgt 50 18.440 ± 7.175 ms/op
MyBenchmark.ZFS_IsDirectory avgt 50 7.635 ± 0.525 ms/op
MyBenchmark.ZFS_IsRegularFile avgt 50 8.249 ± 0.715 ms/op
MyBenchmark.ZFS_Itr avgt 50 13.267 ± 0.571 ms/op
MyBenchmark.ZFS_ToRealPath avgt 50 3.120 ± 0.226 ms/op