Generate automated reports for slow Swift compilation paths in specific targets




Inspired by Brian and Bryan's prior work, we've decided to develop a Swift Package and script to generate automated reports for slow Swift compilation paths in specific targets!

SwiftCompilationPerformanceReporter (nicknamed SwiftCPR) can be configured to build a specific target, output raw debug times to a specific location, and clean those logs to rank the slowest parts to compile.



SwiftCompilationPerformanceReporter can be configured via the config.json file. Below is a description of the options available and a sample configuration:

    // Note: either a project or workspace file can be specified, _but not both_
    "workspacePath": "/Users/jasdev/orangina/Orangina.xcworkspace",
    "projectPath": "/Users/jasdev/orangina/Orangina.xcodeproj",

    "scheme": "Orangina",
    "buildOutputDirectory": "/Users/jasdev/Desktop/CompilationLogs/",
    "reportOutputDirectory": "/Users/jasdev/Desktop/ProcessedLogs/",
    "limit": 10

workspacePath: The absolute path to the workspace file to use.

projectPath: The absolute path to the project file to use.

scheme: The scheme to use

buildOutputDirectory: The directory to store the raw build output files with Swift compilation times.

reportOutputDirectory: The directory to store the processed logs derived from the raw log output.

limit: The number of compilation paths to include in the final results (i.e. the slowest limit paths that compiler handled).


  • Simply clone this repository on the machine that will be generating these reports.
  • Run swift build in the root directory
  • Make sure all directories used in config.json are set properly and exist.
  • If your desired scheme is built with a pre-3.x version of Swift, you'll want to xcode-select back to a stable version (i.e. sudo xcode-select -s /Applications/
  • To kick off the script, run .build/debug/SwiftCompilationPerformanceReporter in the root directory!
  • If there are any errors, the script will output them.
  • The processed logs will be outputted as timestamped files in reportOutputDirectory.


The processed logs will be outputted as a tab separated file with 3 columns after the first line (which holds the total build time). All time units are in seconds.

[Build Time]\t[Path and Line]\t[Detailed Description]

Sample output file:

Total build time: 1214.91016298532
17.0409 /Users/jasdev/orangina/Classes/PerformanceLoggingEvent.swift:278:37 final get {}
7.9331  /Users/jasdev/orangina/Components/ComposeUI/Classes/Election/LeaderboardTableView.swift:71:17   @objc final class func totalHeight(candidates: UInt, allowsLeaderboard: Bool) -> CGFloat
6.2961  /Users/jasdev/orangina/Classes/UniversalLink.swift:127:25   private final class func dictionaryOfAppArgumentsFromQueryString(string: String) -> [NSObject : AnyObject]?
4.2116  /Users/jasdev/orangina/Classes/ActivityViewController.swift:56:22   final get {}