If you want to know what you're seeing: All the way to the right is 0 dB, every thick line is -6, so the display in the screenshot above indicates about -7 dB.
Glitches are probably caused by the CPU usage, I'll try to optimize it (that's why it's turned off by default). One way to optimize it would be to update the displayed level less often.
Thanks, that helps.
A little more info: Not sure what all affects the update rate, but I'm using 150% quality on 3 hyperthreaded cores, at a 144hz refresh rate.
The level can be calculated every 100 ms. Because then there's data from a new 400 ms block with 75% overlap. So, that means that a pretty heavy calculation (look at all previous audio, drop everything that's more than 10 dB below the average, and take the average of what remains) is done every 100 ms. That might be a bit much... Enough to cause a glitch every 100 ms, possibly.
Edit: Reduced update speed to once per second (which is fast enough), doing parts of the calculation on the fly so we don't have to examine everything anymore, at high sample rates (> 48 kHz) reducing it by skipping samples before sending it to the (heavy) resampler. Result: Values are still the same but the effect is almost invisible in the CPU load, even in debug mode
With 192 kHz input,
Old release CPU load with measurement disabled: 0.1%
Old release CPU load with measurement enabled: 4.2%
New debug CPU load with measurement disabled: 1.5%
New debug CPU load with measurement enabled: 2.2%