When GameDroid was originally created, the devices we used for testing couldn't run it much faster than full speed. For this reason (and because it was made for a school project with tight deadlines) we ended up not implementing a frame rate limit.
Now, 5 years later, even low-end smartphones can run the emulator at extremely high speeds, making most games very difficult to play.
A few people have brought this up now so I've decided to fix it. The frame rate is now limited to 60fps by default. The limit can be disabled via a new setting.