Remember the browser wars of the mid 1990s that involved Microsoft Explore and Netscape Navigator? Those were trying times for all of us. This was when Cascading Style Sheets exploded upon the scene and wreaked havoc on all.
Well the browser wars of 2018 promise to be positively deadly and barbaric. May the best browser win and have mercy upon the vanquished.
Mozilla: Firefox 57 is so fast we're calling it Firefox Quantum | ZDNet
I do notice that after a short time, Firefox really lags on opening new tabs or switching to others after having loaded close to 300.
Plan to run a separate install of 57 Beta and see how it does and report back.