Clarification: n was 1000 in the posted test; for some reason the top line was mangled in copy/paste. For n=5000 the results are
5.37185 Second 5.27741 Second 5.41862 Second 3.18303 Second 0.024265 Second
Conclusion: time for the top 4 goes up ~linearly, which suggests that the list is being modified by just appending one item, instead of placing a pointer to it. For the last one it goes up sublinearly.
Reason for worry: in the actual plot package n is not known until the plot is finished. My plotter actually builds dynamically three Graphics3D sublists: faces, edges, points and labels. Optional commands such as changing point size, thickness, colors and font styles, may be inserted at any point in those sublists. So the faster method (preallocating addresses with Table) is ruled out.