StringBuilder.AppendFormat expands to a large code size.

Duplicate code is generated if the same type argument is used.

Large codes are probably not good for JITs.

Performance can be improved by reducing the code size. It can be up to 20% faster.
(Depends on the type arguments used and the number of type arguments.)

Please try running BenchmarkVsReleasedVersion project in your environment.

BenchmarkDotNet=v0.12.1, OS=Windows 10.0.19042
AMD Ryzen 7 3700X, 1 CPU, 16 logical and 8 physical cores
.NET Core SDK=3.1.302
  [Host]   : .NET Core 3.1.6 (CoreCLR 4.700.20.26901, CoreFX 4.700.20.31603), X64 RyuJIT
  ShortRun : .NET Core 3.1.6 (CoreCLR 4.700.20.26901, CoreFX 4.700.20.31603), X64 RyuJIT

Job=ShortRun  IterationCount=1  LaunchCount=1  
WarmupCount=1  

MaximumArgsFormatBenchmark