# \`swift run\` really slow **URL:** \ **Category:** Using Swift\ **Created:** [October 12, 2023, 2:33pm UTC](https://forums.swift.org/t/swift-run-really-slow/67807 "2023-10-12T14:33:44Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![merlindru](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/merlindru/32/32096_2.png) [@merlindru](https://forums.swift.org/u/merlindru)\ **Post date:** [October 12, 2023, 2:33pm UTC](https://forums.swift.org/t/swift-run-really-slow/67807/1 "2023-10-12T14:33:44Z")
Hi! I'm new to Swift development 🙂 Using `swift run` is really slow for me whereas `swift build` and then running the binary isn't. Why is that? Note that I'm using VSCode + the swift CLI, not xcode `swift run` takes 3-ish seconds: ```sh $ time swift run Building for debugging... Build complete! (0.09s) Hello world swift run 0.09s user 0.06s system 4% cpu 3.345 total ``` `swift build` and manually running takes 0.4s: ```sh $ time (swift build && ./.build/debug/api) Building for debugging... Build complete! (0.08s) Hello world ( swift build && ./.build/debug/api; ) 0.00s user 0.00s system 0% cpu 0.427 total ``` Am I doing anything wrong? I'm on MacOS 14.0 ---
**Author:** ![rayx](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/rayx/32/12204_2.png) [@rayx](https://forums.swift.org/u/rayx)\ **Post date:** [October 12, 2023, 3:46pm UTC](https://forums.swift.org/t/swift-run-really-slow/67807/2 "2023-10-12T15:46:43Z")
> [@merlindru](#): > > `swift run 0.09s user 0.06s system 4% cpu 3.345 total` I don't use the command myself, but it appears `swift run` is a wrapper which invokes lots of other commands to do real work. You can run `swift run --vv` to see the details and perhaps find which child process it spends most of the time waiting for on your system. ---
**Author:** ![merlindru](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/merlindru/32/32096_2.png) [@merlindru](https://forums.swift.org/u/merlindru)\ **Post date:** [October 12, 2023, 3:55pm UTC](https://forums.swift.org/t/swift-run-really-slow/67807/3 "2023-10-12T15:55:26Z")
Thanks! It seems to be stuck on this for 3s: ```swift debug: /usr/bin/xcrun --sdk xros --show-sdk-platform-path ``` Do you maybe have any idea what could be causing this? ---
**Author:** ![rayx](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/rayx/32/12204_2.png) [@rayx](https://forums.swift.org/u/rayx)\ **Post date:** [October 12, 2023, 4:02pm UTC](https://forums.swift.org/t/swift-run-really-slow/67807/4 "2023-10-12T16:02:28Z")
I'm not familiar with it. The command runs fine on my system. The general approach to investigate issues like this is using process tracing tool. You can try `dtruss` if you're interested. ---
**Author:** ![merlindru](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/merlindru/32/32096_2.png) [@merlindru](https://forums.swift.org/u/merlindru)\ **Post date:** [October 12, 2023, 4:13pm UTC](https://forums.swift.org/t/swift-run-really-slow/67807/5 "2023-10-12T16:13:33Z")
Thank you :) I really appreciate your help ---
**Author:** ![Farial](https://avatars.discourse-cdn.com/v4/letter/f/3bc359/32.png) [@Farial](https://forums.swift.org/u/Farial)\ **Post date:** [October 12, 2023, 4:26pm UTC](https://forums.swift.org/t/swift-run-really-slow/67807/6 "2023-10-12T16:26:46Z")
Hello, the specific reason seems to be unknown. I suggest that you ensure your versions are the latest to get optimized performance. You may check the Swift version with: **swift --version** ---
**Author:** ![merlindru](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/merlindru/32/32096_2.png) [@merlindru](https://forums.swift.org/u/merlindru)\ **Post date:** [October 12, 2023, 4:57pm UTC](https://forums.swift.org/t/swift-run-really-slow/67807/7 "2023-10-12T16:57:15Z")
I'm on 5.9: ```swift $ swift --version swift-driver version: 1.87.1 Apple Swift version 5.9 (swiftlang-5.9.0.128.108 clang-1500.0.40.1) Target: arm64-apple-macosx14.0 ``` ---
**Author:** ![tokizo](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/tokizo/32/32119_2.png) [@tokizo](https://forums.swift.org/u/tokizo)\ **Post date:** [October 14, 2023, 12:00pm UTC](https://forums.swift.org/t/swift-run-really-slow/67807/8 "2023-10-14T12:00:05Z")
Same for me, it's taking about 3 seconds and it's slow. Swift 5.9. ---
**Author:** ![mickeyl](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/mickeyl/32/12258_2.png) [@mickeyl](https://forums.swift.org/u/mickeyl)\ **Post date:** [October 16, 2023, 8:26am UTC](https://forums.swift.org/t/swift-run-really-slow/67807/9 "2023-10-16T08:26:27Z")
> [@merlindru](#): > > `/usr/bin/xcrun --sdk xros --show-sdk-platform-path` Sounds like it's looking for VisionOS or something. ---
**Author:** ![Jon\_Shier](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/jon_shier/32/921_2.png) [@Jon\_Shier](https://forums.swift.org/u/Jon_Shier)\ **Post date:** [October 16, 2023, 2:44pm UTC](https://forums.swift.org/t/swift-run-really-slow/67807/10 "2023-10-16T14:44:13Z")
Yeah, it seems like all the SDK searches are buggy and error out, at least for me. It can't even find macOS. ```swift ~ % /usr/bin/xcrun --sdk macOS --show-sdk-platform-path 2023-10-16 10:33:35.909 xcodebuild[79763:19248010] Writing error result bundle to /var/folders/c8/jdfwl8sj2f15x8vlx441smjc0000gn/T/ResultBundle_2023-16-10_10-33-0035.xcresult xcodebuild: error: SDK "macOS" cannot be located. 2023-10-16 10:33:37.424 xcodebuild[79765:19248029] Writing error result bundle to /var/folders/c8/jdfwl8sj2f15x8vlx441smjc0000gn/T/ResultBundle_2023-16-10_10-33-0037.xcresult xcodebuild: error: SDK "macOS" cannot be located. xcrun: error: Failed to open property list '/Users/user/macOS/SDKSettings.plist' 2023-10-16 10:33:38.932 xcodebuild[79766:19248044] Writing error result bundle to /var/folders/c8/jdfwl8sj2f15x8vlx441smjc0000gn/T/ResultBundle_2023-16-10_10-33-0038.xcresult xcodebuild: error: SDK "macOS" cannot be located. xcrun: error: unable to lookup item 'PlatformPath' in SDK 'macOS' ``` ---
**Author:** ![Farial](https://avatars.discourse-cdn.com/v4/letter/f/3bc359/32.png) [@Farial](https://forums.swift.org/u/Farial)\ **Post date:** [October 21, 2023, 7:05am UTC](https://forums.swift.org/t/swift-run-really-slow/67807/11 "2023-10-21T07:05:52Z")
@merlindru , Your Swift version is well-updated. The reason seems to be unknown to me. I would suggest that you may trace using dtruss tool on MacOS - this may help to trace and debug. ---
**Author:** ![doozMen](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/doozmen/32/7803_2.png) [@doozMen](https://forums.swift.org/u/doozMen)\ **Post date:** [October 21, 2023, 7:38am UTC](https://forums.swift.org/t/swift-run-really-slow/67807/12 "2023-10-21T07:38:48Z")
I have also noticed before 5.9 swift run was really slow. As I use it in a monorepo to do some jobs in all the packages frequently but the code does not change often I decided to diff the folder and on changes I run `swift run` normally and without changes `swift run --skip-build` this increases the speed but still nog compared to running the executable directly. I would like swift run to do 1. diff for me to see if it should rebuild 2. run the executable It seams to do a lot more and I cannot see why it does that. Thanks for investigating why that is! I will do the same. Could we file a here? [apple/swift-package-manager: The Package Manager for the Swift Programming Language](https://github.com/apple/swift-package-manager) ---
**Author:** ![tokizo](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/tokizo/32/32119_2.png) [@tokizo](https://forums.swift.org/u/tokizo)\ **Post date:** [November 5, 2023, 1:54am UTC](https://forums.swift.org/t/swift-run-really-slow/67807/13 "2023-11-05T01:54:01Z")
Perhaps I found the cause. In conclusion, using regular Xcode, which is not beta, the SDK for VisionOS does not exist, so I saw that the search was taking a long time. I ran swift run on Xcode 15 beta (Xcode 15.1, Build version 15C5042i) and it took less than 0.7 seconds. ```sh $ time (swift run) Building for debugging... Build complete! (0.13s) Hello, world! ( swift run; ) 0.04s user 0.04s system 12% cpu 0.651 total ``` I run `/usr/bin/xcrun --sdk xros --show-sdk-platform-path`, which took a long time to execute, with not beta, beta and compare the execution, the former fails and the latter succeeds. ```bash # not beta $ xcodebuild -version Xcode 15.0.1 Build version 15A507 $ /usr/bin/xcrun --sdk xros --show-sdk-platform-path 2023-11-05 12:36:18.975 xcodebuild[23854:206385] Writing error result bundle to /var/folders/bw/c9dsq_vn3ld19lv5yf57n50m0000gn/T/ResultBundle_2023-05-11_12-36-0018.xcresult xcodebuild: error: SDK "xros" cannot be located. 2023-11-05 12:36:20.426 xcodebuild[23855:206411] Writing error result bundle to /var/folders/bw/c9dsq_vn3ld19lv5yf57n50m0000gn/T/ResultBundle_2023-05-11_12-36-0020.xcresult xcodebuild: error: SDK "xros" cannot be located. xcrun: error: unable to lookup item 'PlatformPath' in SDK 'xros' # beta $ xcodebuild -version Xcode 15.1 Build version 15C5042i $ /usr/bin/xcrun --sdk xros --show-sdk-platform-path /Applications/Xcode-beta2_15_1.app/Contents/Developer/Platforms/XROS.platform ```