Slow and excessive allocation in density and xticks

[Moelf]

using CairoMakie

@time begin
    fig = Figure(size=(800, 400))
    ax = Axis(fig[1,1]; title="inclusive", 
        # xticks=0:50:500,
        yscale=log10)
    barplot!(ax, 50:50:200, fill(15, 4))
    density!(ax, [-1e9];color = (:blue, 0.1), strokecolor = :darkblue, strokewidth = 0.7, label="MC Combination")
    display(fig)
end
#  0.106324 seconds (119.25 k allocations: 15.332 MiB)


@time begin
    fig = Figure(size=(800, 400))
    ax = Axis(fig[1,1]; title="inclusive", 
        xticks=0:50:500,
        yscale=log10)
    barplot!(ax, 50:50:200, fill(15, 4))
    density!(ax, [-1e9];color = (:blue, 0.1), strokecolor = :darkblue, strokewidth = 0.7, label="MC Combination")
    display(fig)
end
# 5.600610 seconds (78.40 k allocations: 11.603 GiB, 12.51% gc time)

cc. @sfranchel this means we shouldn't use the density!() to "fake" a legend element...

[ffreyer]

This is caused by minorticks. They see a step width of 50 from the xticks you set and xlims of -1e9 .. 220 from the plots you create. So they think the (major) ticks are -1e9:50:220, which is 20 million values, each getting 2 ticks. (Technically there is also padding on autolimits so it ends up being a bit more.)

The user side fix would be to call xlims!() before displaying, or set xautolimits = false for the density plot.