Apple announced the Face ID next to the iPhone X and praised its strong security improvements over the Touch ID. But if the security control is activated to the end, face recognition can be slow. So it's faster.
Safety and comfort are usually at odds with each other. Because of this, users use weak passwords, which is why they do not use passwords on their phones. However, Face ID is the exception, as it improves security without being in the way.
How safe is Face ID?
Apple states that there is a 1
Apple also offers the option to only unlock your device when it detects your attention and increases security. If the option is turned on that requires attention, your device will not be unlocked if it can not see your eyes. That means no one can hold your phone to your face as you sleep.
However, this special feature also has its problems. Some types of sunglasses prevent Face ID from seeing your eyes and it takes time to recognize them. It is not long but often a conspicuous one.
Disabling attention detection shortens the time required for the face ID to confirm your identity before you unlock your device. Remember that your iPhone may be unlocked without your knowledge if you disable this feature. However, if the speed advantages are sufficient, disabling is easy.
Disabling Attention Detection
Open Settings, and then tap the Face ID & Passcode button. You must enter your passcode to continue.
Scroll to the section titled ATTENTION and turn the Attention to Face ID switch required to Off.
On the confirmation screen, tap "OK".
Attention Detection is now disabled. Lock your device and turn on the screen to use the new, faster Face ID for a shoot.
Other Attention-Related Extras
Your iPhone and iPad may catch your eye for purposes outside the face ID. You can prevent the screen from dimming and make notifications quieter if they attract your attention.
In the Attention section of the Face ID & Passcode of Settings section, set the Attention-aware Functions switch to the "ON" position. 
Face ID is a great addition to the iPhone and iPad and is constantly improving. It also remains much safer than similar features on Android, even if you disable attention detection.