JIT

Don't use StringLookupSplit in TryGetInstanceAttribute #141

Job	Run time
Interpreter (Debug)	7m 44s
Free-Threaded (Debug) (19)	13m 14s
i686-pc-windows-msvc/msvc (Debug)	17m 51s
i686-pc-windows-msvc/msvc (Release)	10m 52s
x86_64-pc-windows-msvc/msvc (Debug)	18m 0s
x86_64-pc-windows-msvc/msvc (Release)	10m 51s
aarch64-pc-windows-msvc/msvc (Debug)	5m 10s
aarch64-pc-windows-msvc/msvc (Release)	5m 37s
x86_64-apple-darwin/clang (Debug)	13m 41s
x86_64-apple-darwin/clang (Release)	9m 30s
aarch64-apple-darwin/clang (Debug)	8m 48s
aarch64-apple-darwin/clang (Release)	9m 1s
x86_64-unknown-linux-gnu/gcc (Debug)	8m 27s
x86_64-unknown-linux-gnu/gcc (Release)	5m 30s
aarch64-unknown-linux-gnu/gcc (Debug)	10s
aarch64-unknown-linux-gnu/gcc (Release)	9s
	2h 24m 35s

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