I see what you mean now. I think the rendering engine, pygfx, uses asyncio to handle the pre-render functions. I'd need to dig in more to figure out how it can be used with for loops. If you know about async functions and asyncio you might be able to figure it out.

You could also post at pygfx and ask how to modify the Buffer for a WorldObject in a for-loop, since fastplotlib basically abstracts away the buffers and world objects into "plot items" such as images. When you do plot["image"].data = <array> it is basically modifying the buffer for an Image WorldObject and notifying that the buffer data should be uploaded to the GPU.

Thank you very much for the help! It would be very useful to be able to plot while computing.

Is it possible to use an offscreen canvas in fastplotlib? See
pygfx/wgpu-py#471 (comment)