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It was at this point that the second penny dropped and I realised I’d been duped by a graphing misunderstanding and my own enthusiasm for improving frontend performance.
This is the Observer effect, “the disturbance of an observed system by the act of observation”.
I've been fooled several times by this effect, despite having been taught it early on in my school career. 😅
The Dev Tools Performance Monitor Panel
The Performance Monitor collects performance data in realtime and puts it on a graph. It’s handy for detecting performance problems at a high-level.…
I guess we'll (unfortunately) see a lot of turtles in Firefox soon, while browsing the Web with devtools open… 🐢
JUST LANDED in Firefox Nightly:
🐢!
Appears when the server response time for a request exceeds the recommended limit of 500 ms (adjustable in about:config).
Awesome dev work by @b4bomsy and planning by @digitarald & @janodvarko!
If you spot it and it helps, let us know!H
Trys Mudford 
Dave Rupert
