(I have a comment, not really related to your question. I also plot/save similar data and found that these days I could make 3D particle plots much nicer/faster in Make with SSAO enabled (for proper feel of depth). That way one might even just use binary matrix formats for storing as paraview is not needed amymore. Anyway, don’t want to derail the topic!)
On the topic: What exactly is the issue you see? The amount of allocations might be reasonable given that it is an IO task…