I am using
Sweet Home 3D ® Version 5.6 Java version 1.8.0_152 / 64 bit / 1.3 GB max

On Windows 10.

Everything was working fine.

Now whenever I open an existing file, it takes FOREVER to draw each piece of furniture in 2D and 3D view is VERY slow to redraw on a move.

Once in a while I see ...