Huge performance impact

[Steppschuh]

I integrated this library into a project that heavily uses RxJava. Unfortunately enabling the assembly tracking resulted in a non-acceptable performance drop.

Profiling without RxJava2Debug:

Profiling with RxJava2Debug:

The only difference between these two sessions was the line: RxJava2Debug.enableRxJava2AssemblyTracking(new String[]{"my.package.id"});

I understand that this may not be a bug and is simply an implication of the implementation. However, you should clearly note the possible performance impact in the readme.