Improve middleware performance #5930

Job	Run time
Linter	1m 2s
Generate llhttp sources	6s
Test (3.9, ubuntu, false)	6m 9s
Test (3.9, macos, false)	5m 42s
Test (3.9, windows, false)	7m 9s
Test (3.9, Y, ubuntu, false)	7m 23s
Test (3.10, ubuntu, false)	6m 49s
Test (3.10, macos, false)	4m 58s
Test (3.10, windows, false)	7m 6s
Test (3.10, Y, ubuntu, false)	7m 16s
Test (3.11, ubuntu, false)	5m 33s
Test (3.11, macos, false)	4m 45s
Test (3.11, windows, false)	6m 33s
Test (3.11, Y, ubuntu, false)	8m 21s
Test (3.12, ubuntu, false)	6m 59s
Test (3.12, macos, false)	4m 59s
Test (3.12, windows, false)	8m 29s
Test (3.12, Y, ubuntu, false)	7m 44s
Test (pypy-3.9, Y, ubuntu, false)	13m 30s
Test (ubuntu, 3.13, true, Y)	1m 20s
check	1s
Pre-Deploy	0s
Build wheels on ${{ matrix.os }} ${{ matrix.qemu }}	0s
Tarball	0s
Deploy	0s
	2h 1m 54s

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