jit.world @output_matrix 1 = from 60 fps to 15

Hello,
I'm currently trying to render a project (audio and visual) of mine to present it.
Visual parts are regrouped in a jit.world, and audio parts are usingvbap.
Within a couple of hours of documentation I finally got my setup.
I'm using jit.vcr, i'm plugging adc~'s outlets in vcr's 2 first inlets, and plugging the third one with the matrix from the world.

Rest is in the title. Recording maintains a decent framerate, (~-5 fps), but even without recording when I'm enabling @output_matrix I get a terrible framerate. Which is even worse than it sounds considering most of the events are synced with framerate.

My genuine analysis is that the output sets the matrix from GPU to CPU which is why it's such an heavy work. The window doesn't have any problem to display the visuals.
I'm going to try using the @drawto attribute and an asynchronous buffer, but as far as I remember asynchronous buffer, even if lighter, doesn't work very well.

Is there a better way of doing this ? Perhaps using nodes or something ?

EDIT : So after few tests, @drawto + jit.gl.asyncread are helping but I'm still not going over 25 fps. The drawing don't have any effect, however accessing the buffer just kills it.
Size of the matrix seems to have an influence too. I'm recording a big matrix in 32:9 - 3840 * 1080. But adapt project to a smaller size doesn't seem doable.
And I just noticed that it was not recording sound.