Short-circuit update_clims if not necessary (#4743)

Author: BioTurboNick

src/colorbars.jl

@@ -17,7 +17,15 @@ function update_clims(sp::Subplot, op = process_clims(sp[:clims]))::Tuple{Float6
     zmin, zmax = Inf, -Inf
     for series in series_list(sp)
         if series[:colorbar_entry]::Bool
-            zmin, zmax = _update_clims(zmin, zmax, update_clims(series, op)...)
+            # Avoid calling the inner `update_clims` if at all possible; dynamic dispatch hell
+            if (series[:seriestype] ∈ _z_colored_series && series[:z] !== nothing) ||
+               series[:line_z] !== nothing ||
+               series[:marker_z] !== nothing ||
+               series[:fill_z] !== nothing
+                zmin, zmax = _update_clims(zmin, zmax, update_clims(series, op)...)
+            else
+                zmin, zmax = _update_clims(zmin, zmax, NaN, NaN)
+            end
         else
             update_clims(series, op)
         end