Move more than one card at the time
To speed up your playing, there are several ways to move more than one card at the time.
Pick up another card
To pick up another card and add it to the card (or cards) that you are already moving, hold the Ctrl key while you pick up the second card.
If the second card matches, it will be picked up and attached to the cards already being moved.
As an alternative, you can right-click on the second card and it will be picked up and added.
Add a series of matching cards
To add not a single card, but as many cards as will match to the card (or cards) that you are already moving, hold the Shift key while you click on the first card of the series you want to add.
Pick up an entire meld
You can pick up an entire meld from the table if you hold the Shift key while you click on a card in that meld.
As an alternative, you can right-click on the meld, but that only works if you are not moving cards already (otherwise it would pick up just one card).
In much the same way, you can pick up a group of cards from your hand that form a valid meld, only you have to click on the first card of that group.