Contourf vs contour plotting time in CairoMakie

Hello, if I run the code below with contourf and contour, I see two different times:
4.5 seconds and 1.5 seconds, respectively. Is this performance hit expected just filling in the contours?

    using CairoMakie
    using LaTeXStrings
    using PlutoUI
function plotting()
	x = range(-10,10,step=.01)
	y = range(-10,10,step=.01)
	@time z = circles(x,y)
	@time fig, ax, cf =contour(x, y, z, colormap=:greens, fill=true)
	ax.aspect = 1
	return fig
function circles(x_vec, y_vec)
    f(x,y) = x^2 + y^2
    z = [f(x_i, y_i) for x_i in x_vec, y_i in y_vec]
    return z

Yes contourf has to build polygons out of the contour lines that contour just plots as-is. And those polygons currently always get triangulated, even though CairoMakie doesn’t use the triangulation, only GLMakie needs it. I’m not sure which parts account for what percentage of the additional time, though. One could profile it

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interesting, in that case it looks like it may be faster to heatmap, and then plot contours on top?
I guess that ask the question then of why ever use contourf? Perhaps for categorization and not continuous functions?

It looks cleaner than a heatmap I’d say, it doesn’t really have much different information than a heatmap with discrete color map though.