Hi, I was helping out a client and found a weird issue. 2010 iMac, 16GB RAM, 500GB SSD, clean install of OS X High Sierra. This Mac passes all Apple Hardware Tests, the SSD is new, the RAM is good, the GPU is fine as well. I can run Chrome or Safari with a dozen or more tabs open running video and it's fine. I have 6 Adobe CS apps open and testing, it's fine. As soon as I run Firefox and have more than 3 tabs going. the screen goes black or I get the scrambled pink and green video artifacts that point at a failing GPU. Stranger still... with zero other apps installed or system add-ons running, the third time I was able to replicate the behavior, I restarted... and the High Sierra install was broken and I had to reinstall clean from scratch. (A huge waste of my time by the way). I did find the black screen issue in your forums: https://support.mozilla.org/en-US/questions/1219380#answer-1116117 I turned off hardware acceleration, I am running the current video drivers for this Radeon card. I burned an entire day of my life troubleshooting this issue. Because it presented itself as a GPU issue and these 2010 iMacs eventually cook their GPUs, I started there... because I'm not a daily Firefox user, it never occurred to me that your software was at fault. Because I don't want to test your myriad solutions to get back to zero, my recommendation to my client is to not use your product in it's current incarnation on older hardware. As I stated before, Chrome and Safari current versions cause zero problems and frankly, that's a quicker fix.