How would i go about changing color of everything efficiently?

So I'm trying to recreate a sort of thermal vision in my game, Basically, I want it to look somewhat like This, Is there any easy way of doing this? because changing the color of the entire map is quite inefficient and takes time.

You could iterate through every part and change its colour in a small loop.

for i,v in workspace:GetChildren() do
	if v.ClassName == 'Part' then
		v.BrickColor = whatever
	end
end

or you could make a red transparent gui object.