Table of Contents

Mapster includes a benchmark project in src/Benchmark that compares the local Mapster build with AutoMapper, Facet, and Mapperly across several object shapes.

This page is a May 2026 snapshot of those benchmarks. Treat the numbers as a comparison point for this environment and benchmark configuration rather than an absolute guarantee for every machine or application.

How to read the tables

  • Mean is the total time for one BenchmarkDotNet benchmark invocation. Each invocation runs a manual hot loop with MapOperations = 1,000,000.
  • Ns/Map normalizes Mean to the approximate cost of one logical mapping call.
  • Allocated is the memory allocated by one benchmark invocation.
  • Bytes/Map normalizes Allocated to one logical mapping call.
  • Ratio and Alloc Ratio are relative to the default Mapster benchmark in the same scenario.
  • TotalAllTypes runs three mapping scenarios in one benchmark invocation, so its Ns/Map and Bytes/Map values are divided by MapOperations * 3.

Benchmark scenarios

FlatTypes

FlatTypes maps Person -> PersonDTO. It is a flat DTO shape: simple property-to-property copy, no nested objects, and no collections. This scenario mostly highlights mapper call overhead, generated IL quality, and allocation rate for a best-case DTO.

ComplexTypes

ComplexTypes maps Customer -> CustomerDTO. It includes nested address mapping, array/list shape changes, and a flattening rule (AddressCity <- Address.City). This scenario is useful for typical DTOs that combine nested objects, collections, and a small amount of custom member mapping.

RecursiveTypes

RecursiveTypes maps Foo -> FooDTO. The type shape is self-recursive: a Foo can contain another Foo, an enumerable of Foo, and an array of Foo. The sample data does not intentionally create a back-reference cycle, but the mapping graph is deeper and allocates more nested DTOs than the flat or customer scenarios.

TotalAllTypes

TotalAllTypes runs FlatTypes, RecursiveTypes, and ComplexTypes sequentially in one benchmark method. Mean is therefore the total batch time for all three scenarios; use Ns/Map and Bytes/Map for normalized per-map interpretation.

Compared methods

  • Mapster uses the default Mapster expression compiler.
  • Mapster (Roslyn) uses the Roslyn/debug-info compiler path.
  • Mapster (FEC) uses FastExpressionCompiler.
  • Mapster (Codegen) uses generated mapping code.
  • AutoMapper, Facet, and Mapperly are included as external comparison points.
  • Facet (Compiled Projection) uses Facet's compiled projection path, which can behave very differently from the constructor path depending on the object shape.

Results

FlatTypes

Scenario Method MapOperations Mean StdDev Error Ns/Map Ratio Gen0 Allocated Alloc Ratio Bytes/Map
FlatTypes Mapster 10.0.8 1000000 6.849 ms 0.6851 ms 1.0358 ms 6.849 1.01 4781 76.29 MB 1.00 80
FlatTypes Mapster 10.0.8 (Roslyn) 1000000 6.579 ms 0.2782 ms 0.4206 ms 6.579 0.97 4781 76.29 MB 1.00 80
FlatTypes Mapster 10.0.8 (FEC) 1000000 6.549 ms 0.9130 ms 1.3803 ms 6.549 0.97 4781 76.29 MB 1.00 80
FlatTypes Mapster 10.0.8 (Codegen) 1000000 5.868 ms 0.3266 ms 0.5488 ms 5.868 0.86 4781 76.29 MB 1.00 80
FlatTypes AutoMapper 14.0.0 1000000 29.645 ms 0.8963 ms 1.5062 ms 29.645 4.37 4750 76.29 MB 1.00 80
FlatTypes Facet 6.5.5 1000000 7.801 ms 1.0231 ms 1.5467 ms 7.801 1.15 8601 137.33 MB 1.80 144
FlatTypes Facet 6.5.5 (Compiled Projection) 1000000 5.508 ms 0.7064 ms 1.0679 ms 5.508 0.81 4781 76.29 MB 1.00 80
FlatTypes Mapperly 4.3.1 1000000 6.521 ms 0.8369 ms 1.2652 ms 6.521 0.96 4781 76.29 MB 1.00 80

ComplexTypes

Scenario Method MapOperations Mean StdDev Error Ns/Map Ratio Gen0 Gen1 Allocated Alloc Ratio Bytes/Map
ComplexTypes Mapster 10.0.8 1000000 78.59 ms 1.519 ms 2.553 ms 78.586 1.00 28111 - 450.13 MB 1.00 472
ComplexTypes Mapster 10.0.8 (Roslyn) 1000000 53.48 ms 1.760 ms 2.958 ms 53.475 0.68 25818 - 411.99 MB 0.92 432
ComplexTypes Mapster 10.0.8 (FEC) 1000000 69.29 ms 1.539 ms 2.326 ms 69.288 0.88 28200 - 450.13 MB 1.00 472
ComplexTypes Mapster 10.0.8 (Codegen) 1000000 51.86 ms 2.514 ms 3.801 ms 51.863 0.66 25750 - 411.99 MB 0.92 432
ComplexTypes AutoMapper 14.0.0 1000000 112.27 ms 4.516 ms 7.590 ms 112.270 1.43 29142 - 465.39 MB 1.03 488
ComplexTypes Facet 6.5.5 1000000 446.72 ms 51.706 ms 78.172 ms 446.725 5.69 175000 500 2792.36 MB 6.20 2928
ComplexTypes Facet 6.5.5 (Compiled Projection) 1000000 678.87 ms 42.646 ms 64.474 ms 678.868 8.64 44000 - 709.53 MB 1.58 744
ComplexTypes Mapperly 4.3.1 1000000 52.81 ms 1.134 ms 1.714 ms 52.812 0.67 25769 - 411.99 MB 0.92 432

RecursiveTypes

Scenario Method MapOperations Mean StdDev Error Ns/Map Ratio Gen0 Gen1 Allocated Alloc Ratio Bytes/Map
RecursiveTypes Mapster 10.0.8 1000000 404.49 ms 63.593 ms 96.14 ms 404.486 1.02 49000 - 793.46 MB 1.00 832
RecursiveTypes Mapster 10.0.8 (Roslyn) 1000000 383.00 ms 34.563 ms 52.25 ms 382.999 0.97 49000 - 793.46 MB 1.00 832
RecursiveTypes Mapster 10.0.8 (FEC) 1000000 84.82 ms 10.777 ms 16.29 ms 84.816 0.21 45875 125 732.42 MB 0.92 768
RecursiveTypes Mapster 10.0.8 (Codegen) 1000000 82.81 ms 11.104 ms 16.79 ms 82.806 0.21 49625 125 793.46 MB 1.00 832
RecursiveTypes AutoMapper 14.0.0 1000000 585.42 ms 88.660 ms 134.04 ms 585.425 1.48 168000 1000 2693.18 MB 3.39 2824
RecursiveTypes Facet 6.5.5 1000000 302.24 ms 9.444 ms 18.06 ms 302.241 0.76 150000 666 2395.63 MB 3.02 2512
RecursiveTypes Facet 6.5.5 (Compiled Projection) 1000000 708.77 ms 58.207 ms 88.00 ms 708.770 1.79 73000 - 1174.93 MB 1.48 1232
RecursiveTypes Mapperly 4.3.1 1000000 116.05 ms 16.639 ms 25.16 ms 116.055 0.29 68833 166 1098.63 MB 1.38 1152

TotalAllTypes

Scenario Method MapOperations Mean StdDev Error Ns/Map Ratio Gen0 Gen1 Allocated Alloc Ratio Bytes/Map
TotalAllTypes Mapster 10.0.8 1000000 413.9 ms 16.88 ms 25.52 ms 137.97 1.00 82000 - 1.29 GB 1.00 461
TotalAllTypes Mapster 10.0.8 (Roslyn) 1000000 546.4 ms 29.01 ms 43.86 ms 182.12 1.32 80000 - 1.25 GB 0.97 448
TotalAllTypes Mapster 10.0.8 (FEC) 1000000 155.7 ms 24.48 ms 37.01 ms 51.91 0.38 78800 - 1.23 GB 0.95 440
TotalAllTypes Mapster 10.0.8 (Codegen) 1000000 117.4 ms 8.56 ms 12.94 ms 39.14 0.28 80250 - 1.25 GB 0.97 448
TotalAllTypes AutoMapper 14.0.0 1000000 681.4 ms 76.25 ms 115.27 ms 227.13 1.65 202000 1000 3.16 GB 2.45 1130
TotalAllTypes Facet 6.5.5 1000000 677.4 ms 33.30 ms 55.96 ms 225.80 1.64 329000 1000 5.14 GB 3.99 1840
TotalAllTypes Facet 6.5.5 (Compiled Projection) 1000000 1,337.4 ms 42.95 ms 64.94 ms 445.81 3.24 122000 - 1.91 GB 1.49 685
TotalAllTypes Mapperly 4.3.1 1000000 141.5 ms 3.04 ms 5.81 ms 47.10 0.34 99250 250 1.55 GB 1.20 554

Interpretation notes

  • The fastest method depends on the object shape. Flat DTOs mostly measure low-level call overhead; recursive graphs and collection-heavy DTOs shift the bottleneck toward nested object creation and collection mapping.
  • Facet constructor and compiled-projection paths are shown separately because they exercise different APIs and can trade CPU time for allocation behavior differently across scenarios.
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