[davidhewitt]

Change Summary

I was looking at cleaning up the json_key methods a bit (they create a lot of temporary String allocations). I found that these datetime methods needed particular work to clean up, so I'm pushing this first and separately:

• Use serializer.collect_str(s) instead of serializer.serialize_str(&s.to_string())
• Add fast paths for converting exact datetime types to speedate types without having to go through Python attributes.

Related issue number

N/A

Checklist

• The pull request title is a good summary of the changes - it will be used in the changelog
• Unit tests for the changes exist
• Tests pass on CI
• Documentation reflects the changes where applicable
• My PR is ready to review, please add a comment including the phrase "please review" to assign reviewers

[codspeed]

CodSpeed Performance Report

Merging #12626 will degrade performances by 10.44%

_{Comparing dh/dt-optimization (3038c43) with main (0329e09)}

Summary

⚡ 7 improvements
❌ 1 regression
✅ 203 untouched

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
⚡	test_core_future	18.4 µs	15.9 µs	+15.74%
⚡	test_date_from_datetime	23.7 µs	19.1 µs	+23.64%
⚡	test_core_future	26.3 µs	22.3 µs	+18%
❌	test_list_of_strs_json_uncached	378.8 µs	423 µs	-10.44%
⚡	test_north_star_dump_json	29.7 ms	26.7 ms	+10.9%
⚡	test_datetime_milliseconds	26.2 µs	21.5 µs	+22.07%
⚡	test_datetime	29 µs	24.2 µs	+19.66%
⚡	test_datetime_seconds	26.1 µs	21.6 µs	+20.93%

[github-actions]

Coverage report

This PR does not seem to contain any modification to coverable code.

[davidhewitt]

Regression is unrelated volatility, all the gains are relevant and real 🎉