How I may see server-timing in the devtools?

Developer Tools
#1

According to MDN FF support server-timing.
So it should actually show Server-Timings in the network panel, like this:

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Screenshot 2019-04-15 at 16.07.32.png964×803 177 KB

When I send the header

Server-Timing: cache;desc="Cache Read";dur=23.2

But it don’t.
Maybe I need to set some flag, or something?

#2

This header is obviously not visible in the Network Monitor yet, see bug 1403051 .

What is available, is the PerformanceServerTiming API, which at least allows you to output the info to the console (see the example on that page).

Sebastian