rune: More perf work #1837

Job	Run time
docs	2m 54s
msrv	1m 40s
clippy	2m 6s
nightly	3m 30s
rustfmt	16s
basics	1s
wasm	1m 16s
test_miri (rune)	3m 33s
no_std (ubuntu-latest, minimal)	1m 11s
test_miri (rune-core)	44s
build_feature (alloc)	3m 25s
test_doc	6m 12s
test_miri (rune-alloc)	5m 57s
build_feature (cli)	3m 58s
build_feature (cli,doc)	3m 55s
no_std (macos-latest, minimal)	1m 7s
test_lib	4m 11s
build_feature (cli,fmt)	3m 51s
test_rune	3m 0s
build_feature (doc)	3m 35s
build_feature (workspace)	3m 24s
build_feature (languageserver)	3m 47s
build_feature (byte-code)	3m 23s
build_feature (capture-io)	3m 21s
build_feature (emit)	3m 23s
	1h 13m 40s

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