There might not be a GPU available capable of that. Also the CPU is heavily loaded. To speed up the rendering, set surface.SuppressLighting = true, FadeAway = 0, ColorSaturation = 100.
Remember to launch app with Ctrl + F5 to prevent debugger intervention. You may need to reduce the resolution of the data, to say 2000 x 400 in 3D to be able to update it rapidly.
You may find 2D spectrogram view more usable with hi-resolution spectrogram data:

- Hi-resolution spectrogram 8000x400
- hi-res_spectrogram.jpg (407.16 KiB) Viewed 4490 times