Profile, fix, and verify: Improve app responsiveness with Instruments

A Podkey summary of Profile, fix, and verify: Improve app responsiveness with Instruments, from WWDC 2026.A lot of this episode comes down to one very practical lesson: the first tool that seems to explain a slowdown is not always telling the whole story. The big themes here are how to read Instruments more accurately, how a Swift runtime detail can quietly eat CPU, and how to catch main-thread hangs that barely show up in the profiler you probably reached for first. There’s also a nice thread running through all of it, which is that better labeling and better comparisons can turn performance work from vague guesswork into something much more concrete.When Time Profiler tells only half the storySystem Trace catches the blocked main threadWhy signposts make profiling sanerFlame graphs are great until they aren’tThe Swift existential overhead that finally stood outRun Comparisons turns improvement into proofMain Actor contention hiding in plain sightProfile the build people actually useThis podcast was created with Podkey. Make your own at https://podkey.fm