Android Studio 2.2.1: Slow Debugging

check your break-points added to your code for debugging before, I fixed this problem with release break-points that added on UI function

See this, it helped me massively:

Intellij Debugger slow: Method breakpoints my dramatically slow down debugging

I was waiting up to a minute when debugging for the first webservice call to return. CPU and memory monitors peaked during this period. Removed the Java Method Breakpoints and hey presto, back to normal.

Make sure your debugger option is correct.