PaulRB:
Well, I know you read post #1, because you commented in post #3 that the OP had not answered my question. So I was wondering if you know of a way to avoid the problem I described in post #1, like some code or library which does not require 3 bytes of ram per led, but instead allows generating those 3 bytes "on the fly" just before they are sent to the strip. I know that's possible, I remember reading that someone had achieved that in the past, but I can't find that thread.
I think I misunderstood your first post.
I would be interested if you find that thread again.