ArcMap slow?

ArcMap was extremly slow on my PC. Opening attribute tables, the Add Data dialog box, a model oder even a toolbox took ages (such as opening a toolbox > 30secs).
Now, I'm used to applying "Windows Classic" design in order to speed up things.
Turns out - since switching back to standard Windows 7 design ArcMap performance has improved significantly on my machine! Opening a larger model now only takes 1-2 secs (if at all)!

ArcMap 10.3, Windows 7

Excel Pivot table - manually reorder rows

Header > Sort Options > manually

Then:
- click into cell of row you want to move
- open context menu > "move"

 
Excel 2013