Why is there a delay when unlocking a file?

When generating a key from the user’s master password, a high number of rounds is used by the key derivation function (KDF) to create an intentional delay. By default, the key is calculated in about 200,000 rounds, which makes it more time-consuming for an attacker to try different passwords in a brute force attack. The iteration count that causes the delay can be changed by the menu command File | Master password & encryption settings. It is recommended to keep the iteration count such that it will cause at least a 1-second delay, but even better is more, as high as is tolerable when opening files. You can also set the iteration count to a low value to eliminate the delay, but that is not recommended as it weakens security.

Note: Mobile devices have less computing power, so calculating a key on a mobile device will usually take a few times longer than on a desktop PC. If you also use a mobile device, you’ll need to keep that in mind when specifying the iteration count.