As a new developer, I think I fall into this trap a lot! I always don't want to touch other people's methods or introduce bugs, so I only make tiny, tiny little changes before thoroughly testing everything. It really slows me down.
You should be slow with other people's code. I bet that if you work on something solo you'd be much faster and that is because you're intimate with the code, you know what could go wrong, where, etc..
Second, the slowness comes from the fact it takes a lot more time to read and understand code that to write it, let alone trust that it is doing what is doing correctly. If you don't introduce bugs and are very careful you won't have nightmarish surprises. Keep up.
Good! You should be slow. Slow and deliberate. Break stuff (not in production!) and watch how it breaks. Learn from your mistakes. Right now you're laying the foundation of your confidence as a developer. That confidence is built upon your failures and your successes. Have fun newbie!
