Thanks Ashley for the suggestion on what we can do to help with this issue. I opened a github issue to track this here https://github.com/Scirra/Construct-3-bugs/issues/552 but my first attempt to record performance failed. I think the process of recording caused the performance to drop to nothing and my screen sat loading sprites and recording for 15 mins.
I will continue to add to that github issue if I can get some more information and would encourage other's experiencing this issue to add their comments to the issue.
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OK, will follow this up on the GitHub issue.
EDIT: Submitted the issue to GitHub, we moved it over to the GC team, they found that it was a pretty big issue with Chrome, and are rolling out a patch to the latest beta (which I believe can be found in Canary).