Regarding Swift type inference compile-time performance

Xcode 12.5.1:

Benchmark #1: xcrun swiftc -Xfrontend -disable-access-control -Xfrontend -disable-availability-checking -disallow-use-new-driver -typecheck a.swift
  Time (mean ± σ):      59.6 ms ±   1.0 ms    [User: 41.4 ms, System: 15.6 ms]
  Range (min … max):    58.0 ms …  62.5 ms    48 runs
 
Benchmark #1: xcrun swiftc -Xfrontend -disable-access-control -Xfrontend -disable-availability-checking -disallow-use-new-driver -typecheck b.swift
  Time (mean ± σ):     102.4 ms ±   1.4 ms    [User: 83.1 ms, System: 16.5 ms]
  Range (min … max):   100.3 ms … 105.6 ms    28 runs
 
Benchmark #1: xcrun swiftc -Xfrontend -disable-access-control -Xfrontend -disable-availability-checking -disallow-use-new-driver -typecheck c.swift
  Time (mean ± σ):     443.9 ms ±   5.3 ms    [User: 412.2 ms, System: 29.1 ms]
  Range (min … max):   436.8 ms … 453.9 ms    10 runs
 
Benchmark #1: xcrun swiftc -Xfrontend -disable-access-control -Xfrontend -disable-availability-checking -disallow-use-new-driver -typecheck d.swift
  Time (mean ± σ):      94.8 ms ±   1.5 ms    [User: 74.9 ms, System: 17.4 ms]
  Range (min … max):    92.1 ms …  97.7 ms    30 runs

Xcode 13b1:

Benchmark #1: xcrun swiftc -Xfrontend -disable-access-control -Xfrontend -disable-availability-checking -disallow-use-new-driver -typecheck a.swift
  Time (mean ± σ):      64.1 ms ±   0.9 ms    [User: 45.3 ms, System: 15.4 ms]
  Range (min … max):    62.3 ms …  65.9 ms    44 runs
 
Benchmark #1: xcrun swiftc -Xfrontend -disable-access-control -Xfrontend -disable-availability-checking -disallow-use-new-driver -typecheck b.swift
  Time (mean ± σ):     108.4 ms ±   1.5 ms    [User: 88.5 ms, System: 16.8 ms]
  Range (min … max):   105.8 ms … 112.5 ms    27 runs
 
Benchmark #1: xcrun swiftc -Xfrontend -disable-access-control -Xfrontend -disable-availability-checking -disallow-use-new-driver -typecheck c.swift
  Time (mean ± σ):     532.7 ms ±   4.7 ms    [User: 498.2 ms, System: 31.6 ms]
  Range (min … max):   522.3 ms … 539.2 ms    10 runs
 
Benchmark #1: xcrun swiftc -Xfrontend -disable-access-control -Xfrontend -disable-availability-checking -disallow-use-new-driver -typecheck d.swift
  Time (mean ± σ):      99.2 ms ±   1.8 ms    [User: 78.6 ms, System: 18.2 ms]
  Range (min … max):    96.9 ms … 106.2 ms    29 runs

6/14 5.5 Toolchain:

Benchmark #1: /Library/Developer/Toolchains/swift-5.5-DEVELOPMENT-SNAPSHOT-2021-06-14-a.xctoolchain/usr/bin/swiftc -Xfrontend -disable-access-control -Xfrontend -disable-availability-checking -disallow-use-new-driver -typecheck a.swift
  Time (mean ± σ):      79.0 ms ±   1.1 ms    [User: 57.1 ms, System: 16.3 ms]
  Range (min … max):    76.7 ms …  81.2 ms    37 runs
 
Benchmark #1: /Library/Developer/Toolchains/swift-5.5-DEVELOPMENT-SNAPSHOT-2021-06-14-a.xctoolchain/usr/bin/swiftc -Xfrontend -disable-access-control -Xfrontend -disable-availability-checking -disallow-use-new-driver -typecheck b.swift
  Time (mean ± σ):     129.6 ms ±   1.4 ms    [User: 106.6 ms, System: 19.0 ms]
  Range (min … max):   126.7 ms … 132.4 ms    22 runs
 
Benchmark #1: /Library/Developer/Toolchains/swift-5.5-DEVELOPMENT-SNAPSHOT-2021-06-14-a.xctoolchain/usr/bin/swiftc -Xfrontend -disable-access-control -Xfrontend -disable-availability-checking -disallow-use-new-driver -typecheck c.swift
  Time (mean ± σ):     662.6 ms ±   5.4 ms    [User: 623.5 ms, System: 33.9 ms]
  Range (min … max):   655.7 ms … 672.9 ms    10 runs
 
Benchmark #1: /Library/Developer/Toolchains/swift-5.5-DEVELOPMENT-SNAPSHOT-2021-06-14-a.xctoolchain/usr/bin/swiftc -Xfrontend -disable-access-control -Xfrontend -disable-availability-checking -disallow-use-new-driver -typecheck d.swift
  Time (mean ± σ):     118.6 ms ±   1.9 ms    [User: 95.0 ms, System: 18.6 ms]
  Range (min … max):   115.6 ms … 122.5 ms    24 runs

Local release build, no assertions:

Benchmark #1: /Users/jshier/Desktop/Code/swift/build/Ninja-Release/swift-macosx-x86_64/bin/swiftc -Xfrontend -disable-access-control -Xfrontend -disable-availability-checking -disallow-use-new-driver -typecheck a.swift
  Time (mean ± σ):      60.1 ms ±   0.7 ms    [User: 47.0 ms, System: 10.3 ms]
  Range (min … max):    58.3 ms …  61.7 ms    48 runs
 
Benchmark #1: /Users/jshier/Desktop/Code/swift/build/Ninja-Release/swift-macosx-x86_64/bin/swiftc -Xfrontend -disable-access-control -Xfrontend -disable-availability-checking -disallow-use-new-driver -typecheck b.swift
  Time (mean ± σ):     110.2 ms ±   1.3 ms    [User: 96.1 ms, System: 11.2 ms]
  Range (min … max):   108.0 ms … 113.7 ms    26 runs
 
Benchmark #1: /Users/jshier/Desktop/Code/swift/build/Ninja-Release/swift-macosx-x86_64/bin/swiftc -Xfrontend -disable-access-control -Xfrontend -disable-availability-checking -disallow-use-new-driver -typecheck c.swift
  Time (mean ± σ):     557.6 ms ±   5.7 ms    [User: 528.8 ms, System: 25.2 ms]
  Range (min … max):   544.9 ms … 565.3 ms    10 runs
 
Benchmark #1: /Users/jshier/Desktop/Code/swift/build/Ninja-Release/swift-macosx-x86_64/bin/swiftc -Xfrontend -disable-access-control -Xfrontend -disable-availability-checking -disallow-use-new-driver -typecheck d.swift
  Time (mean ± σ):      99.1 ms ±   1.3 ms    [User: 84.2 ms, System: 12.2 ms]
  Range (min … max):    97.2 ms … 102.8 ms    29 runs