New keyboard shortcuts in draw.io
As new features are added to draw.io and the menu is refined, new keyboard shortcuts are also built into the editor. Here are some of the new and useful shortcuts for diagramming in draw.io.
Move selected remote shapes and connectors
Select the shapes and connectors you want to move, then hold Shift+Alt+drag and drag the cursor to reposition the selection even if it is not currently under the cursor.

Increase/decrease font size
Select a shape or connector or label, and press Ctrl+Shift +/- (NumPad) to increase or decrease the text size. This only works with the + and - keys on the number pad.

Increase/decrease shape size
Select a shape, and press Ctrl+Shift+arrow key to increase or decrease the right or lower edge of the shape.

Clear all extra waypoints on a connector
Select a connector and press Alt+Shift+R to reset the waypoints back to the default path.

More keyboard shortcuts in draw.io
There are many other mouse + keyboard shortcut combinations in draw.io to help you diagram faster, as well as many other key combinations.
Next time you go through the draw.io menu, or right-click and open the context menu, check and see if there is a keyboard shortcut next to the command you want to use.

Here's a one-page reference sheet that you can print out containing the most common and useful keyboard shortcuts in draw.io.