This is what the docs say:
About emulator performance
Because the Android emulator must simulate the ARM instruction set architecture on your computer and the WXGA screen is significantly larger than what the emulator normally handles, emulator performance is much slower than usual.
In particular, initializing the emulator can be slow and can take several minutes, depending on your hardware. When the emulator is booting there is limited user feedback, so please be patient and continue waiting until you see the home screen appear.
We're working hard to resolve the performance issues in the emulator and it will improve in future releases. In the meantime, we wanted to give developers access to new APIs and an basic test environment as early as possible.
Keeping in mind that performance on the emulator does not reflect the speed or performance of apps on actual devices running Android 3.0, developing and testing on the emulator is still an important tool in evaluating your application's appearance and functionality on the new platform.