When not to use Base64 encoding

It has been my long voyage to find where we have use base64 encoding. Recently I was developing an android app where I have get encoded (base64 encoded) from server and displays them in ListView.
The app performance was annoying I have make my app behave properly. After long brain storming I have found some interesting result which I want to share with you guys.

Here are some of my findings

• base64 encoding makes file size roughly 33% larger than their original binary representation.
• base64 encoded data may possible take more resources(memory + CPU).

I will update my result later.