Significant speed reduction with XCode 11.2 vs 8.1

My "mac build machine" is running XCode 8.1.0, and I noticed that the binaries built (with the same flags) on my MBP with XCode 11.2 (and also 9.1) are much slower for a specific app. Like 10x slower.


Again: the same exact sources, the same exact compiler flags. But the version built on my MBP w/ XCode 11 is signifcantly slower than the version built on my Mac Mini w/ XCode 8.


The **** is, I can't install 8.1 on my MBP, because apparently it won't run on Mojave. And I can't install even 9.1 on the dev machine, since it's running Sierra.


What I wanted to try was 8.1 on my MBP, to see if the actual problem is the compilers; but I can't figure out how to make that work.


I'd be most grateful for some way to determine what the actual problem is. I did notice that on running jtool2 -L against both binaries (on my MBP), I get the curious result that they link different actual code at runtime:


  /System/Library/Frameworks/AppKit.framework/Versions/C/AppKit 
(compatibility version 45.0.0, current version 1504.82.104)
(compatibility version 45.0.0, current version 1671.60.109)
/System/Library/Frameworks/ApplicationServices.framework/Versions/A/ApplicationServices
(compatibility version 1.0.0, current version 48.0.0)
(compatibility version 1.0.0, current version 50.1.0)
/System/Library/Frameworks/Carbon.framework/Versions/A/Carbon
(compatibility version 2.0.0, current version 157.0.0)
(compatibility version 2.0.0, current version 158.0.0)
/System/Library/Frameworks/Cocoa.framework/Versions/A/Cocoa
(compatibility version 1.0.0, current version 22.0.0)
(compatibility version 1.0.0, current version 23.0.0)
/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation
(compatibility version 150.0.0, current version 1349.65.0)
(compatibility version 150.0.0, current version 1575.23.0)
/System/Library/Frameworks/CoreLocation.framework/Versions/A/CoreLocation
(compatibility version 1.0.0, current version 2101.0.62)
(compatibility version 1.0.0, current version 2245.16.14)
/System/Library/Frameworks/CoreServices.framework/Versions/A/CoreServices
(compatibility version 1.0.0, current version 775.19.0)
(compatibility version 1.0.0, current version 946.0.0)
/System/Library/Frameworks/Foundation.framework/Versions/C/Foundation
(compatibility version 300.0.0, current version 1349.64.0)
(compatibility version 300.0.0, current version 1575.23.0)
/System/Library/Frameworks/Security.framework/Versions/A/Security
(compatibility version 1.0.0, current version 57740.51.3)
(compatibility version 1.0.0, current version 58286.255.3)
/System/Library/Frameworks/WebKit.framework/Versions/A/WebKit
(compatibility version 1.0.0, current version 603.1.30)
(compatibility version 1.0.0, current version 607.3.9)
/usr/lib/libSystem.B.dylib
(compatibility version 1.0.0, current version 1238.51.1)
(compatibility version 1.0.0, current version 1252.250.1)
/usr/lib/libc++.1.dylib
(compatibility version 1.0.0, current version 307.5.0)
(compatibility version 1.0.0, current version 400.9.4)
/usr/lib/libcups.2.dylib
(compatibility version 2.0.0, current version 2.12.0)
(compatibility version 2.0.0, current version 2.13.0)

Replies

How much RAM available ?

16GB

I have a MBP with 16 GB and did not notice slowdown.


Have you several versions of XCode installed on MBP ?

I've installed the latest Xcode as well as 9.4.1 with the same results. I tried to install a ver 8, but it cannot run on Mojave as far as I can tell. At least, I haven't been able to get it to run.

Have you renamed XCode when you install several version ?

Yes, of course.