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movermeyer merged 1 commit into from
Nov 12, 2025
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Update benchmarks for fair python-dateutil #174

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78 changes: 39 additions & 39 deletions README.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -84,42 +84,42 @@ Parsing a timestamp with no time zone information (e.g., ``2014-01-09T21:48:00``
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
| Module |Python 3.14|Python 3.13|Python 3.12|Python 3.11|Relative slowdown (versus ciso8601, latest Python)|…|Python 3.10|Python 3.9|Python 3.8|
+================================+===========+===========+===========+===========+==================================================+=+===========+==========+==========+
|ciso8601 |26.4 nsec |23.4 nsec |24.5 nsec |25.4 nsec |N/A |…|35.9 nsec |35.6 nsec |37 nsec |
|ciso8601 |69.3 nsec |60.4 nsec |64.8 nsec |59.5 nsec |N/A |…|89.4 nsec |85.7 nsec |93.5 nsec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|backports.datetime_fromisoformat|N/A |N/A |N/A |N/A |0.8x |…|30.3 nsec |30.7 nsec |32 nsec |
|backports.datetime_fromisoformat|N/A |N/A |N/A |N/A |0.9x |…|76.4 nsec |71.6 nsec |79 nsec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|datetime (builtin) |51.5 nsec |48 nsec |54.8 nsec |53.9 nsec |2.0x |…|N/A |N/A |N/A |
|datetime (builtin) |125 nsec |123 nsec |136 nsec |127 nsec |1.8x |…|N/A |N/A |N/A |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|udatetime |269 nsec |277 nsec |277 nsec |280 nsec |10.2x |…|280 nsec |279 nsec |280 nsec |
|udatetime |543 nsec |543 nsec |538 nsec |520 nsec |7.8x |…|544 nsec |544 nsec |553 nsec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|str2date |1.4 usec |1.42 usec |1.59 usec |1.59 usec |52.9x |…|1.62 usec |1.64 usec |1.76 usec |
|python-dateutil |3.14 usec |3.41 usec |4.03 usec |3.46 usec |45.3x |…|4.14 usec |4.16 usec |4.22 usec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|pendulum |1.74 usec |65.2 nsec |64.8 nsec |64.7 nsec |65.8x |…|64.6 nsec |66.4 nsec |86.4 nsec |
|str2date |3.21 usec |3.28 usec |3.61 usec |3.51 usec |46.3x |…|3.76 usec |3.71 usec |3.91 usec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|iso8601 |2.13 usec |2.2 usec |2.35 usec |2.1 usec |80.6x |…|2.3 usec |2.31 usec |2.47 usec |
|pendulum |4.19 usec |152 nsec |126 nsec |136 nsec |60.4x |…|148 nsec |145 nsec |181 nsec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|iso8601utils |N/A |N/A |N/A |N/A |61.5x |…|N/A |2.19 usec |2.51 usec |
|iso8601utils |N/A |N/A |N/A |N/A |53.9x |…|N/A |4.62 usec |5.05 usec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|isodate |2.36 usec |2.52 usec |2.78 usec |2.18 usec |89.3x |…|2.41 usec |2.4 usec |2.49 usec |
|iso8601 |4.97 usec |5.14 usec |5.37 usec |5.33 usec |71.6x |…|5.21 usec |5.25 usec |5.7 usec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|PySO8601 |3.55 usec |3.79 usec |3.79 usec |3.11 usec |134.6x |…|3.94 usec |3.64 usec |6.79 usec |
|isodate |5.24 usec |5.72 usec |5.9 usec |5.53 usec |75.6x |…|5.61 usec |5.81 usec |6.07 usec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|aniso8601 |4.32 usec |4.74 usec |4.95 usec |4.37 usec |163.9x |…|5.53 usec |5.19 usec |5.72 usec |
|PySO8601 |9.56 usec |10.2 usec |9.53 usec |7.99 usec |137.9x |…|9.53 usec |9.98 usec |27.8 usec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|zulu |4.71 usec |4.63 usec |5.12 usec |4.54 usec |178.7x |…|5.17 usec |4.93 usec |5.17 usec |
|aniso8601 |12.2 usec |12.3 usec |12.9 usec |11.7 usec |175.7x |…|15.5 usec |16 usec |15.7 usec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|python-dateutil |10.3 usec |11.4 usec |12.6 usec |11.9 usec |390.4x |…|14.9 usec |15.3 usec |15.8 usec |
|zulu |12.4 usec |12.5 usec |13.8 usec |13.1 usec |178.3x |…|14.3 usec |14.6 usec |14.3 usec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|arrow |13.3 usec |13.4 usec |14.7 usec |13.5 usec |503.5x |…|16.7 usec |16.2 usec |17.4 usec |
|arrow |42.5 usec |42.9 usec |42.4 usec |42.5 usec |612.6x |…|49.8 usec |50.1 usec |49.1 usec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|maya |13.7 usec |10.9 usec |14.7 usec |12.7 usec |520.0x |…|15.7 usec |14.5 usec |16 usec |
|maya |46.6 usec |35.4 usec |42.5 usec |39.1 usec |671.5x |…|44.1 usec |44.8 usec |46.7 usec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|metomi-isodatetime |335 usec |345 usec |353 usec |359 usec |12687.0x |…|480 usec |468 usec |508 usec |
|metomi-isodatetime |808 usec |852 usec |810 usec |831 usec |11647.5x |…|1.1 msec |1.09 msec |1.11 msec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|moment |487 usec |502 usec |525 usec |503 usec |18471.2x |…|563 usec |559 usec |576 usec |
|moment |1.22 msec |1.3 msec |1.3 msec |1.38 msec |17631.5x |…|1.36 msec |1.4 msec |1.39 msec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+

ciso8601 takes 26.4 nsec, which is **2.0x faster than datetime (builtin)**, the next fastest Python 3.14 parser in this comparison.
ciso8601 takes 69.3 nsec, which is **1.8x faster than datetime (builtin)**, the next fastest Python 3.14 parser in this comparison.

.. </include:benchmark_with_no_time_zone.rst>

Expand All @@ -132,55 +132,55 @@ Parsing a timestamp with time zone information (e.g., ``2014-01-09T21:48:00-05:3
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
| Module |Python 3.14|Python 3.13|Python 3.12|Python 3.11|Relative slowdown (versus ciso8601, latest Python)|…|Python 3.10|Python 3.9|Python 3.8|
+================================+===========+===========+===========+===========+==================================================+=+===========+==========+==========+
|ciso8601 |30.7 nsec |27.8 nsec |27.9 nsec |29.3 nsec |N/A |…|39 nsec |39.4 nsec |40.2 nsec |
|ciso8601 |71.8 nsec |70.3 nsec |75.1 nsec |67.3 nsec |N/A |…|98.3 nsec |92.9 nsec |97.8 nsec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|backports.datetime_fromisoformat|N/A |N/A |N/A |N/A |1.2x |…|46.6 nsec |48.4 nsec |49.1 nsec |
|backports.datetime_fromisoformat|N/A |N/A |N/A |N/A |1.1x |…|103 nsec |99.1 nsec |102 nsec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|datetime (builtin) |81.6 nsec |72.7 nsec |77.8 nsec |68.8 nsec |2.7x |…|N/A |N/A |N/A |
|datetime (builtin) |197 nsec |197 nsec |199 nsec |179 nsec |2.7x |…|N/A |N/A |N/A |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|udatetime |344 nsec |321 nsec |334 nsec |332 nsec |11.2x |…|331 nsec |332 nsec |336 nsec |
|udatetime |661 nsec |638 nsec |664 nsec |643 nsec |9.2x |…|669 nsec |664 nsec |669 nsec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|str2date |1.67 usec |1.73 usec |1.94 usec |1.77 usec |54.2x |…|1.96 usec |1.94 usec |2.08 usec |
|str2date |4.04 usec |3.91 usec |4.38 usec |4.49 usec |56.2x |…|4.66 usec |4.81 usec |4.9 usec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|pendulum |2.48 usec |104 nsec |104 nsec |104 nsec |80.7x |…|106 nsec |105 nsec |130 nsec |
|python-dateutil |4.95 usec |5.61 usec |6.33 usec |5.73 usec |68.9x |…|6.87 usec |6.85 usec |7.17 usec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|iso8601 |3.04 usec |3.24 usec |3.42 usec |3.06 usec |98.7x |…|3.17 usec |3.18 usec |3.52 usec |
|pendulum |6.53 usec |202 nsec |200 nsec |210 nsec |91.0x |…|222 nsec |221 nsec |262 nsec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|isodate |3.14 usec |3.16 usec |3.39 usec |2.88 usec |102.3x |…|3.1 usec |3.12 usec |3.26 usec |
|isodate |7.5 usec |7.79 usec |8.26 usec |7.74 usec |104.4x |…|7.76 usec |7.8 usec |8.4 usec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|iso8601utils |N/A |N/A |N/A |N/A |126.4x |…|N/A |4.98 usec |5.3 usec |
|iso8601 |7.79 usec |7.71 usec |8.37 usec |7.92 usec |108.4x |…|7.65 usec |7.69 usec |7.98 usec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|PySO8601 |5.11 usec |5.23 usec |5.67 usec |4.75 usec |166.3x |…|5.31 usec |5.23 usec |5.72 usec |
|iso8601utils |N/A |N/A |N/A |N/A |143.3x |…|N/A |13.3 usec |14.4 usec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|zulu |5.47 usec |5.66 usec |6.08 usec |5.26 usec |177.9x |…|5.85 usec |5.83 usec |5.96 usec |
|PySO8601 |15.8 usec |16 usec |16.7 usec |14.6 usec |219.7x |…|16.1 usec |16.2 usec |16.7 usec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|aniso8601 |5.96 usec |6.42 usec |7.19 usec |6.18 usec |194.0x |…|7.56 usec |7.26 usec |7.91 usec |
|zulu |16.6 usec |16.2 usec |17.1 usec |15.9 usec |230.9x |…|17.2 usec |17.2 usec |17.4 usec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|python-dateutil |13.2 usec |14.6 usec |15.6 usec |15.9 usec |428.8x |…|19.7 usec |20 usec |20.6 usec |
|aniso8601 |17.6 usec |17.8 usec |19 usec |17.4 usec |244.8x |…|21.7 usec |22.8 usec |22.8 usec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|arrow |15.6 usec |16.3 usec |19.5 usec |16.1 usec |507.7x |…|20 usec |19.3 usec |19.9 usec |
|arrow |49 usec |52.1 usec |52 usec |49.7 usec |682.3x |…|58.8 usec |58 usec |58.5 usec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|maya |15.8 usec |12 usec |14.4 usec |12.4 usec |512.7x |…|15 usec |14.7 usec |15.1 usec |
|maya |54.2 usec |41.4 usec |44.6 usec |39.6 usec |755.5x |…|45.3 usec |45.7 usec |46.1 usec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|metomi-isodatetime |329 usec |346 usec |342 usec |335 usec |10692.8x |…|475 usec |482 usec |487 usec |
|metomi-isodatetime |794 usec |870 usec |806 usec |806 usec |11055.0x |…|1.1 msec |1.09 msec |1.15 msec |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+
|moment |❌ |❌ |❌ |❌ |2112732.4x |…|❌ |❌ |❌ |
|moment |❌ |❌ |❌ |❌ |2163866.8x |…|❌ |❌ |❌ |
+--------------------------------+-----------+-----------+-----------+-----------+--------------------------------------------------+-+-----------+----------+----------+

ciso8601 takes 30.7 nsec, which is **2.7x faster than datetime (builtin)**, the next fastest Python 3.14 parser in this comparison.
ciso8601 takes 71.8 nsec, which is **2.7x faster than datetime (builtin)**, the next fastest Python 3.14 parser in this comparison.

.. </include:benchmark_with_time_zone.rst>

.. <include:benchmark_module_versions.rst>

Tested on Linux 6.14.10-orbstack-00291-g1b252bd3edea using the following modules:
Tested on Linux 6.17.4-orbstack-00308-g195e9689a04f using the following modules:

.. code:: python

aniso8601==10.0.1
arrow==1.3.0
arrow==1.4.0
backports.datetime_fromisoformat==2.0.3
ciso8601==2.3.2
ciso8601==2.3.3
iso8601==2.1.0
iso8601utils==0.1.2
isodate==0.7.2
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