gh-145192: Improve performance of PySequence_GetSlice #2517

Job	Run time
aarch64-apple-darwin/clang	9m 2s
x86_64-pc-windows-msvc/msvc-free-threading	5m 17s
x86_64-apple-darwin/clang	15m 14s
x86_64-unknown-linux-gnu/gcc-free-threading	8m 23s
aarch64-unknown-linux-gnu/gcc	7m 30s
x86_64-pc-windows-msvc/msvc	10m 26s
x86_64-unknown-linux-gnu/gcc	9m 49s
	1h 5m 41s

Provide feedback