V1.2102 might use more video memory in some cases than 1.2047.
The difference between the 2 versions is that the 1.2047 used simple vector array to draw the toolpath and the 1.2102 using vertex buffer object (VBO).
Usually VBO is faster and is more efficient than vector arrays, because the vectors data is put into the VBO which is in the VRAM and a pointer is used to use the object later.
So, the VBO needs no updates and so it is fast especially on large arrays of vertices (large toolpath). Vector arrays usually have to be updated. (It is a bit complicated to explain so I don't go into more details now...)
But you have to remember that OpenGL is just a standard and how well and efficient the different methods work depends on the video card manufacturer, I mean how well they implemented the different methods.
Usually manufacturers follow the standards closely and implementing things pretty well, but sometimes there are bugs in different methods.
Just an example in many integrated Intel GPUs the line smoothing works pretty rought. When enabling line smoothing on those cards the lines not getting smoothed, but instead they getting even more pixellated.
So, I can think of that VBO handling is not implemented properly on the graphic card you have.
Is it is mini PC or can you fit another graphic card to try?
And RAM usage has not much to do with the issue I described previously. The VRAM needed by the UCCNC is only about 200Mbytes and so you will not see in RAM usage if this data is in the RAM and is copied continously back and forth between the RAM and VRAM. And OpenGL handling these things automatically without any programmer code. The programmer can only advice (give a hints) to OpenGL to possible what to do if something is wrong, but you cannot tell OpenGL exactly what to do in case of issues. OpenGL is who finally will decide.
OpenGL is really complex, so it is a bit hard for me to describe these things, I can say it is about as complicated as coding motion control.
One idea I have is that you could try this little software tool:
https://www.techpowerup.com/gpuz/It shows properties of the graphics card like the GPU and VRAM usage.