For most of these, the key combinations can be customized by altering input-config.json.

Alt+Enter Toggle display between full-screen and windowed
Up arrow Open text log (history)
Ctrl Hold to skip (previously read text)
Ctrl+Shift Hold to skip (read+unread text)
Ctrl+PageDown Skip to the next choice or end of script file
F7 Toggle display of performance statistics

Debug mode only

These shortcuts only function while debug mode is enabled (by setting debug=true in config.ini.

F3 Clear cached resources
Ctrl+F5 Reload resources and restart
F12 Saves a screenshot to the ./save folder
Numpad + Quicksave (slot 99)
Numpad - Quickload (slot 99)