So yeah after the post A Nuclear Reactor Accident in All Your CPU
here an example of consequences.
iPhone performance benchmarks after Spectre security update
Apple released iOS 11.2.2 update to address Spectre security issues. I was curious about the actual performance change. So I’ve benchmarked my iPhone before and after the security fix. Here are the results side-by-side to give you a clear view how the performance has changed due to the Spectre vulnerability.
and here the general results for an iPhone 6
outch ~40% slower
So even if you thought that Meltdown and/or Spectre did not affect you somehow I can tell you they do affect you.
Because you publish apps on systems and those systems probably gonna get patched and so have their performance reduced by almost half.
Testing for performance will be even more important in the future.