Win7 64bit, NVIDIA GeForce GTX TITAN X 12GB
Tested on Blender 2.79, 2.78c, 2.77a, happens in all of them.
Exact steps for others to reproduce the error
- Put on animation playback, Alt+A
- On Solid Viewport Shading, the fps should be 60fps or more when panning and orbiting around in Blender
- Put on Textured Viewport Shading, Alt+Z, goes to really slow 1-2fps, which is expected, I guess, which sucks -> moving on
- Put on again Solid Viewport Shading, Alt+Z, goes to ~15-20fps, which is undesired and weird, since it just was over 60 fps
- If you select one of the mesh-branches and do Undo, Ctrl+Z, the speed jumps up to more than 60fps, which is desired
So, something happens when you go out of Textured Viewport shading mode, something is dragging down the fps for Solid Viewport Shading, until you do the Undo.