It's slow because it's trying to run the ARM version of Android, not the Intel version. So your computer is pretending to run code for chips it doesn't have. The genymotion or intel images for the emulator will allow your computer to use code written for Intel chips, so it runs much faster. I use Genymotion, it allows you to emulate many different screen sizes on lots of different virtual devices and android versions. The free version works great, but when you get more serious upgrading to the paid version may be a good idea.