in one of the software I'm responsible, I'm trying to get rid of an outdated version of 3D visualisation library and would like to use Qt3D to do the job.
I started with a simple (at least that's what I though) application: points in space are generated and their colour should change according to some criteria. Before I used 2 projections and QGraphicsView to represent the data.
I am on Windows 10, using MSVC 2013 with Qt 5.6.2 64bits.
For each generated points I use a spherical mesh (the same for each point), set the material and transformation. The thing I see is that for about 1300 points the memory usage for the application goes up to something like 2 GB, but after a while it goes down to something like 80 MB!

I could imagine 1300 meshes are a lot, this is why I only use 1 instance of QSphereMesh and QPhongMaterial (I only use 1 colour at this stage) which are used by my 1300 QEntity instances, and I reduced the spherical mesh quality (anyway they will be looked at from far away). But still I find a bit odd that the memory behaves like this.

Is this normal? If yes, is there smarter way of coding this in order to reduce the initial memory usage?

Please find a test project illustrating the aforementioned behaviour:
.pro file
Windows.h
Windows.cpp
mainwindow.h
mainwindow.cpp
main.cpp