Beautiful graphics, great idea, very customizable - and causes the "FirefoxCP WebServer" thread to run at 100% on all procs, fans to kick in, and the entire system crawls to a halt even after closing Firefox (process doesn't close when Firefox exits). Verified on 2 iMacs running High Sierra the latest version of LST and Firefox 59.0.2. Disabled the add-on and the CPU's stay normal, the fans don't kick in, and I can use my computers again. It's a shame that it does this because it's a beautiful add on. :(