rune: Performance improvements #1836

Job	Run time
docs	2m 57s
clippy	2m 10s
msrv	1m 30s
nightly	3m 19s
rustfmt	15s
basics	1s
test_miri (rune)	3m 26s
wasm	1m 12s
no_std (ubuntu-latest, minimal)	1m 12s
build_feature (alloc)	3m 16s
test_miri (rune-core)	42s
no_std (macos-latest, minimal)	1m 16s
test_doc	6m 10s
build_feature (cli)	4m 15s
test_miri (rune-alloc)	5m 57s
build_feature (cli,doc)	3m 55s
build_feature (cli,fmt)	3m 57s
test_lib	5m 22s
test_rune	2m 55s
build_feature (doc)	3m 46s
build_feature (workspace)	3m 31s
build_feature (languageserver)	3m 50s
build_feature (byte-code)	3m 31s
build_feature (capture-io)	3m 31s
build_feature (emit)	3m 21s
	1h 15m 17s

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