Hi, 

I am trying to optimize my website (because my current ranking on PageSpeed Insights is horrible) and I am following along with your video tutorial. However, the Critical.exe file is not working. 

When I downloaded the program, I got the most recent version, but I got numerous notifications and warnings from my firewall saying that the program was "risky" and telling me NOT to allow your program access to my computer. Normally, I would have heeded that warning but I thought I could trust the application and allowed it regardless. Another firewall notice popped up after and again, I allowed the program. When the program finally loaded, it was just a blank screen. There was no place to enter my URL and purchase code as your video showed. I have tried clicking the "Force Reload", but again, nothing happens. I have tried closing the program, running a cleaner on my computer and reopening and still, nothing happens. No matter what I do, I am greeted with a blank screen. 

 So now I'm not sure what to do and I'm concerned about the holes your program has put in my firewall. I still need to optimize my site. Please advise.