Is my code incorrect or the library performance doesn't look good yet?

[qrilka]

In https://github.com/qrilka/xeno/tree/hw-xml I've tried out checking the speed of this library using xeno's benchmark and the results do look good:

Benchmark xeno-speed-bench: RUNNING...
benchmarking 4KB/hexml-dom
time                 8.383 μs   (8.317 μs .. 8.490 μs)
                     0.996 R²   (0.990 R² .. 1.000 R²)
mean                 8.957 μs   (8.500 μs .. 10.30 μs)
std dev              2.929 μs   (982.9 ns .. 5.410 μs)
variance introduced by outliers: 99% (severely inflated)
             
benchmarking 4KB/xeno-sax
time                 5.581 μs   (5.511 μs .. 5.723 μs)
                     0.998 R²   (0.995 R² .. 1.000 R²)
mean                 5.555 μs   (5.514 μs .. 5.653 μs)
std dev              194.7 ns   (37.90 ns .. 317.9 ns)
variance introduced by outliers: 44% (moderately inflated)
             
benchmarking 4KB/xeno-dom
time                 12.06 μs   (11.96 μs .. 12.19 μs)
                     0.997 R²   (0.992 R² .. 0.999 R²)
mean                 12.47 μs   (11.98 μs .. 13.77 μs)
std dev              2.255 μs   (356.3 ns .. 4.429 μs)
variance introduced by outliers: 95% (severely inflated)
             
benchmarking 4KB/hexpat-sax
time                 86.28 μs   (85.62 μs .. 87.26 μs)
                     0.998 R²   (0.995 R² .. 1.000 R²)
mean                 89.36 μs   (86.01 μs .. 101.3 μs)
std dev              19.03 μs   (1.717 μs .. 39.61 μs)
variance introduced by outliers: 96% (severely inflated)
             
benchmarking 4KB/hexpat-dom
time                 244.2 μs   (238.2 μs .. 253.5 μs)
                     0.993 R²   (0.987 R² .. 0.998 R²)
mean                 247.3 μs   (240.2 μs .. 261.4 μs)
std dev              32.73 μs   (15.55 μs .. 64.88 μs)
variance introduced by outliers: 87% (severely inflated)
             
benchmarking 4KB/xml-dom
time                 1.570 ms   (1.500 ms .. 1.698 ms)
                     0.972 R²   (0.937 R² .. 0.998 R²)
mean                 1.556 ms   (1.520 ms .. 1.647 ms)
std dev              179.0 μs   (118.1 μs .. 288.0 μs)
variance introduced by outliers: 76% (severely inflated)
             
benchmarking 4KB/hw-xml
time                 4.577 ms   (4.460 ms .. 4.742 ms)
                     0.992 R²   (0.985 R² .. 0.999 R²)
mean                 4.729 ms   (4.647 ms .. 4.954 ms)
std dev              419.5 μs   (168.8 μs .. 822.1 μs)
variance introduced by outliers: 56% (severely inflated)
             
benchmarking 31KB/hexml-dom
time                 9.684 μs   (9.507 μs .. 9.879 μs)
                     0.995 R²   (0.991 R² .. 0.999 R²)
mean                 9.676 μs   (9.514 μs .. 10.06 μs)
std dev              792.4 ns   (317.9 ns .. 1.400 μs)
variance introduced by outliers: 81% (severely inflated)
             
benchmarking 31KB/xeno-sax
time                 3.104 μs   (3.096 μs .. 3.118 μs)
                     0.999 R²   (0.996 R² .. 1.000 R²)
mean                 3.127 μs   (3.086 μs .. 3.289 μs)
std dev              250.3 ns   (20.50 ns .. 529.4 ns)
variance introduced by outliers: 82% (severely inflated)
             
benchmarking 31KB/xeno-dom
time                 6.896 μs   (6.766 μs .. 7.040 μs)
                     0.995 R²   (0.991 R² .. 0.998 R²)
mean                 6.885 μs   (6.755 μs .. 7.236 μs)
std dev              661.6 ns   (332.9 ns .. 1.242 μs)
variance introduced by outliers: 86% (severely inflated)
             
benchmarking 31KB/hexpat-sax
time                 325.0 μs   (318.3 μs .. 332.8 μs)
                     0.995 R²   (0.987 R² .. 0.999 R²)
mean                 324.5 μs   (317.7 μs .. 364.3 μs)
std dev              37.12 μs   (10.68 μs .. 90.66 μs)
variance introduced by outliers: 83% (severely inflated)
             
benchmarking 31KB/hexpat-dom
time                 338.7 μs   (331.1 μs .. 346.3 μs)
                     0.997 R²   (0.996 R² .. 0.999 R²)
mean                 330.5 μs   (327.7 μs .. 335.1 μs)
std dev              12.75 μs   (8.609 μs .. 21.02 μs)
variance introduced by outliers: 33% (moderately inflated)
             
benchmarking 31KB/xml-dom
time                 9.997 ms   (9.712 ms .. 10.26 ms)
                     0.994 R²   (0.988 R² .. 0.999 R²)
mean                 10.12 ms   (9.963 ms .. 10.63 ms)
std dev              676.0 μs   (244.9 μs .. 1.325 ms)
variance introduced by outliers: 35% (moderately inflated)
             
benchmarking 31KB/hw-xml
time                 4.885 ms   (4.756 ms .. 5.093 ms)
                     0.986 R²   (0.972 R² .. 0.998 R²)
mean                 5.036 ms   (4.945 ms .. 5.241 ms)
std dev              385.7 μs   (208.2 μs .. 627.5 μs)
variance introduced by outliers: 47% (moderately inflated)
             
benchmarking 211KB/hexml-dom
time                 275.5 μs   (271.2 μs .. 280.5 μs)
                     0.993 R²   (0.985 R² .. 0.998 R²)
mean                 284.0 μs   (274.8 μs .. 308.7 μs)
std dev              53.75 μs   (24.99 μs .. 101.4 μs)
variance introduced by outliers: 93% (severely inflated)
             
benchmarking 211KB/xeno-sax
time                 270.4 μs   (265.8 μs .. 277.6 μs)
                     0.997 R²   (0.994 R² .. 1.000 R²)
mean                 267.8 μs   (265.6 μs .. 272.9 μs)
std dev              10.43 μs   (6.226 μs .. 16.04 μs)
variance introduced by outliers: 36% (moderately inflated)
             
benchmarking 211KB/xeno-dom
time                 656.8 μs   (639.0 μs .. 684.0 μs)
                     0.993 R²   (0.987 R² .. 0.999 R²)
mean                 662.5 μs   (648.2 μs .. 690.1 μs)
std dev              68.16 μs   (39.50 μs .. 109.0 μs)
variance introduced by outliers: 76% (severely inflated)
             
benchmarking 211KB/hexpat-sax
time                 20.91 ms   (19.94 ms .. 21.96 ms)
                     0.992 R²   (0.980 R² .. 0.999 R²)
mean                 20.29 ms   (20.01 ms .. 20.71 ms)
std dev              800.1 μs   (447.5 μs .. 1.352 ms)
variance introduced by outliers: 13% (moderately inflated)
             
benchmarking 211KB/hexpat-dom
time                 20.98 ms   (20.28 ms .. 21.61 ms)
                     0.994 R²   (0.987 R² .. 0.999 R²)
mean                 21.59 ms   (21.14 ms .. 23.10 ms)
std dev              1.696 ms   (411.2 μs .. 3.287 ms)
variance introduced by outliers: 32% (moderately inflated)
             
benchmarking 211KB/xml-dom
time                 79.71 ms   (77.20 ms .. 82.52 ms)
                     0.998 R²   (0.996 R² .. 1.000 R²)
mean                 82.44 ms   (80.94 ms .. 86.60 ms)
std dev              3.960 ms   (1.051 ms .. 6.437 ms)
             
benchmarking 211KB/hw-xml
time                 11.96 ms   (11.67 ms .. 12.30 ms)
                     0.995 R²   (0.991 R² .. 0.999 R²)
mean                 12.11 ms   (11.90 ms .. 12.54 ms)
std dev              700.6 μs   (383.0 μs .. 1.143 ms)
variance introduced by outliers: 27% (moderately inflated)
             
Benchmark xeno-speed-bench: FINISH

As the library has almost no docs I've used the example in app/Main.hs

[qrilka]

Also there is https://github.com/haskell-perf/xml and it could make sense to include hw-xml there as a comparison too.