What is APK size and download size?

A large APK has no relationship of slow runtime performance . It depends how you manage the resources. However, a large APK does impact Sales Performance, as users prefer to download smaller apps in Google Market.

It is true that mobile application users are not much concerned about navigating across the mobile screen, vertically or horizontally, as long as they get the content they need. Still, many times it is found that the size really matters when it comes to overall user experience .

Because the APK files install apps on your system, they can pose a serious security threat . A person will malicious intentions could modify the APK before you install it, then use it as a digital Trojan horse to install and run malware.

Android projects (in general) contain source code, which gets compiled to class files that end up in the APK. Compiled files are smaller than the source code – for example they strip all the comments out of the file (you do include comments in your source files don’t you!)