To understand this we have a lot to consider from the host PC to how color printing works.

My background involves apps that dealt with translating color from a fixed RGB level to a color on the LCD. This turned out to take a lot of time in the CPU as we calculated the closest color we had in the LCD color palette.

-> There's also so very old issues with XP and IDE DMA but your post seems to omit all the PC details so I can't guess if that's in play here.

At least it works. Your post seems to just note it has to think about it.
Bob