Current situation: graphics in 256-bit color depth (greyscale). Walls and floor represented by 0..256 grey tones.
Target situation: graphics in bitmap for devices with monochrome displays (using ordered dithering)
Any performance optimisations needed. First of all, the dithering option slowing down rendering. Maybe it need to use pure canvas instead of a p5js library, or use off-screen buffer to draw.
And for the mobile devices or slow computers frame rate can be beter then now.