Android Studio Emulator: Intel Atom x86 vs ARM

Intel-based devices can run the full range of Android apps, even ones that were originally written for the ARM architecture. However, if an app contains ARM-specific code, then it must be translated before it can be executed.

This takes time and energy to do, so battery life and overall performance may suffer. Whether this is a serious problem is up for debate: our reviews indicate that Intel does tend to trail behind ARM in battery life, but the gap isn’t huge, and overall performance is generally very good.

At any rate, Intel is working hard to encourage developers to produce Intel-native versions of their apps, so hopefully translation will become progressively less of an issue.

Source: http://www.alphr.com/features/390064/arm-vs-intel-processors-what-s-the-difference

It says, "Running an x86 base Android Virtual Device is 10x faster"- while trying to run an arm virtual device. So I guess, x86 is faster.