Update

You can now enable the Quick Boot option for Android Emulator. That will save emulator state, and it will start the emulator quickly on the next boot.

Click on Emulator edit button, then click Show Advanced Setting. Then enable Quick Boot like below screenshot.

Quick boot

Android Development Tools (ADT) 9.0.0 (or later) has a feature that allows you to save state of the AVD (emulator), and you can start your emulator instantly. You have to enable this feature while creating a new AVD or you can just create it later by editing the AVD.

Also I have increased the Device RAM Size to 1024 which results in a very fast emulator.

Refer to the given below screenshots for more information.

Creating a new AVD with the save snapshot feature.

Android emulator with save snapshot feature.

Launching the emulator from the snapshot.

Launching the emulator from the snapshot.

And for speeding up your emulator you can refer to Speed up your Android Emulator! :