The correct answer should be: "Check and test if all possibilities for using the software are able to work properly".
Explanation:
There are some reasons for a software to not work properly or for taking a long time to load, such as the speed of your internet connection, the amount of pages and/or software running in your computer at the same time, the "age" of your hardware, your hardware and/or software cache, and more. You need to check and test if all these possibilities are real reasons or not for making your software to take a long time to load and work properly; one or another may be the reason for that.
