I've just made a quick test with the 4096FFT (using the files goldhausen has provided). It seems to work ok with the ILI9341_t3n Library (using frame buffer) I get 22 FPS.
I'm using the Audio Library and have no issues with using the 4096FFT.

In my project I would like to visualize the audio spectrum pre and post filtering (20 Hz ... 20kHz).
As you can see on the picture, my frequency-axis is not linear. I try to get better resolution especially in the lower frequency range (20 Hz ... 320 Hz), therefore the 4096FFT gets handy with a Frequency Bin resolution of ca. 11 Hz.
Although this works, I agree with DD4WH, the "ZoomFFT" would be a much better approach to solve this "low-frequency" problem.

Is there a "ready to use" ZoomFFT library available that works with the audio library?

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