I made a release here to describe the improvement backported. I figured I'd write about the change in output once we land PUP-10150 and do so there (since that ticket will be applicable to the release notes for both 5.5.x & 6.x. Lemme know if that's wrong.
Puppet manifests that make use of stdlib's `deprecation` function, use the pseudo keywords `break`, `return`, and `next`, experience serialization warnings, or have custom Ruby code that makes use of the `PuppetStack.top_of_stack` function should see a marked increase in performance.
Yes, this ticket was a performance improvement that has already gone out in the last Platform release (6.11?). Now it will also be going out in 5.5.x and 6.4.x. It caused a regression in stacktrace printing which will be fixed in 6.12, along with that fix we introduced the new feature of the "puppet_trace" setting. 5.5.x & 6.4.x won't see the regression but will get the new "puppet_trace" output option.
Puppet manifests that make use of stdlib's `deprecation` function, use the pseudo keywords `break`, `return`, and `next`, experience serialization warnings, or have custom Ruby code that makes use of the `PuppetStack.top_of_stack` function should see a marked increase in performance.
---
Release note: Performance of manifests that use the `PuppetStack.top_of_stack` function have been greatly improved. This includes manifests that use the puppetlabs-stdlib `deprecation` function or the pseudo keywords `break`, `return`, and `next`. [PUP-10170](https://tickets.puppetlabs.com/browse/PUP-10170)