[codeonfire]

Well, I would get PyCharm for this particular issue. In these cases you are usually going to have to search all files for variable names or classes. Learn all the keystrokes for finding references and viewing class and call trees. If you are going to be owning the code add some type hinting comments for the classes and functions that you deal with frequently.

[mrfusion]

Agreed being able to click function calls and see their definition is huge. Also find the back button so you can get back to where you were.

Other than that it just takes time and practice to learn a large code base. It's basically a new kind of reading you need to train yourself to do.