I made a module to create film grain using the edible images API. You might face some problems as I haven’t tested everything, but it should all work.
The way it works is that it makes a pool of like 20 created film grain images and then reuses them (if the variable is true) and once the pool is filled then you can speed the effect up without any performance loss.
Links to it:
Video - Can’t upload since it’s like 10.01 MB
Model - Film Grain Model