[tobias-tengler]

Variable coercion decoded every JSON property name and enum string into a UTF-16 string for the field and value lookups, and the literal pass created a new NameNode per coerced field.

FieldCollection<T> and EnumValueCollection now look names up as UTF-8 bytes: collections with up to eight entries are scanned with Ascii.Equals, larger ones widen the name into a stack buffer and use the frozen dictionary's ReadOnlySpan<char> alternate lookup. The enum lookup honors the configurable name comparer and only decodes the string for custom comparers. The input parser and the coercion helper use these lookups, the literal pass reuses the schema's enum name and a NameNode cached on InputField, and processed fields are tracked by index instead of a pooled string set.

Benchmarks

Measured with a local VariableCoercionBenchmark (not part of this PR), net11 in-process.

Small input (2 objects, 5 fields)

Method	Version	Mean	Ratio	Allocated	Alloc Ratio
Variable coercion	main	1.312 μs	1.00	3.33 KB	1.00
Variable coercion	PR	0.995 μs	0.76	2.31 KB	0.69

Large input with a list of 20 input objects (22 objects, 66 fields)

Method	Version	Mean	Ratio	Allocated	Alloc Ratio
Variable coercion	main	15.979 μs	1.00	36.09 KB	1.00
Variable coercion	PR	11.870 μs	0.74	24.13 KB	0.67

Single enum value

Method	Version	Mean	Ratio	Allocated	Alloc Ratio
Variable coercion	main	133.5 ns	1.00	480 B	1.00
Variable coercion	PR	132.7 ns	0.99	416 B	0.87

List of 20 enum values (12-value enum)

Method	Version	Mean	Ratio	Allocated	Alloc Ratio
Variable coercion	main	1.947 μs	1.00	5,200 B	1.00
Variable coercion	PR	2.118 μs	1.09	3,632 B	0.70

Variable coercion allocates 31% less for the small input and 33% less for the large input, and is 24% and 26% faster. A single enum value allocates 13% less at the same speed. A list of 20 values of a 12-value enum allocates 30% less but is 9% slower, because the hashed lookup fetches the alternate lookup per call; caching it, together with a cached enum literal, follows in a separate PR.

[github-actions]

Patch coverage

100.0% of changed lines covered (95/95)

File	Covered	Changed	Patch %
…/src/Types/Execution/Processing/VariableCoercionHelper.cs	15	15	100.0% 🟢
src/HotChocolate/Core/src/Types/Types/EnumType.cs	9	9	100.0% 🟢
src/HotChocolate/Core/src/Types/Types/EnumValueCollection.cs	25	25	100.0% 🟢
src/HotChocolate/Core/src/Types/Types/FieldCollection.cs	21	21	100.0% 🟢
src/HotChocolate/Core/src/Types/Types/InputField.cs	2	2	100.0% 🟢
src/HotChocolate/Core/src/Types/Types/InputParser.cs	23	23	100.0% 🟢

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Project coverage: 58.7% (315762/538284 lines)

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