Update: see article on Medium (out-of-date since accelerated Intel CPUs now available).
This project shows emulators running on accelerated Intel CPUs and on emulated ARM CPUs on travis with their run times.
Click on the travis and cirrus badges to find out the time it takes to run an android test on an emulator.
Note: there are many emulator configurations that have not been tried.
Feel free to submit an issue or a PR if you find more emulators that run on travis.