Holy crap! Having my Logitech Performance MX mouse double-click every time I single clicked was THE MOST FRUSTRATING issue I've ever had with ANY computer mouse.
Before getting into how to fix the double-click issue, I want to say that I love this mouse. LOVE it. In fact, this was the third Performance MX I've owned and the issue only popped up with the third one, AND only after about 2-3 years of use. So, before you go all barbarian on your mouse and start slamming it on the desk (guilty), or wanting to throw it out the window (I so wanted to), just know that this CAN BE FIXED. Here's what I found out.
This is a mechanical issue NOT a software issue.
In simple terms, there's a small curved copper piece inside the mouse that, over time and generous use, flattens out. When this happens, tension is decreased and there's less separation (or even none) when the left mouse button is clicked > resulting in a double click instead of a single click.
Here's how to fix it.
1. Take apart the Performance MX mouse.
Level of difficulty: 2
Hardest part: Removing the plastic pads without ruining them.
2. Repair mouse with double click problem
Follow these step-by-step instructions
Level of difficulty: 6
Hardest part: Increasing the curve on the copper plate to increase tension. TIP: Take your time and go REALLY SLOW because if you break the copper piece, you're hosed.
I followed the above steps and was able to fix my beloved Logitech mouse in about 45 minutes. It's now back to being a healthy clicking beast and I can go back to work.