Behind the screen
Virtual DM screen
Set up the rolls you need before the session, then run the whole fight without typing. Every roll keeps the name you gave it, so you are looking for Dragon Breath, not for 18d6.
Dice bags
A bag is a set of rolls that belong together. Build one per encounter, per monster or per character: a Goblin Encounter bag with the attack, damage and initiative already in it means the whole fight runs without you touching notation once.
One action can hold several rolls. A longsword keeps its attack and its damage side by side, because reaching for them separately is what slows a turn down.
Nothing leaves your device
There is no account and no sync. Your bags are stored in this browser, which means they are private and they work with no connection at all, but it also means they will not follow you to another device yet.