Thanks to a new feature in Firefox, you can understand that it is "slow" program or cause problems. This unusual feature is called Firefox Health Report. It takes minutes, "health" of the browser, collect performance metrics and stability. Using the program, you can report to find out exactly when there were problems and provide tips on optimization.
In addition, there is the opportunity to compare how bad it is on your computer compared to other users. If desired, you can simply disable the function.