improve perf of asString #1180

Job	Run time
test / Dependency Review	5s
test / Lint Code	21s
test / Check Licenses	22s
test / Test (14, macos-latest)	2m 1s
test / Test (14, ubuntu-latest)	56s
test / Test (16, macos-latest)	1m 6s
test / Test (16, ubuntu-latest)	55s
test / Test (16, windows-latest)	1m 31s
test / Test (18, macos-latest)	1m 10s
test / Test (18, ubuntu-latest)	52s
test / Test (18, windows-latest)	2m 11s
test / Test (20, macos-latest)	1m 18s
test / Test (20, ubuntu-latest)	1m 1s
test / Test (20, windows-latest)	1m 43s
test / Automerge Dependabot PRs	0s
	15m 32s

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