Slow plotting of spectrogram

[Anton1]

Good day, Uwe.
I've done program that could be an example after some changes.
I give a link to the archive: https://cloud.mail.ru/public/LPcx/a7VbvrFGx
Now the program is running slowly, but I hope that it is possible to optimize.
Thank you in advance.

[Uwe]

Not sure what this tarball is supposed to be - looks like some downstripped version of your application, but without doing anything. To be honest I was interested in some simple data factory, that can be used for a waterfall plot - and this part is unfortunately missing.

But at least it shows the implementation of your SpectrogramData::value(), that explains why you have a worse image composition performance than the spectrogram example. Regardless of any further optimization I recommend to speed this one up. As it is called for every pixel it is worth to spend some time on writing it in a performant way.

Uwe