Using a Core2 Duo E7500 (Q1'09) and this is a noticeable improvement; but I still find chrome faster in that the GUI doesn't stall. Firefox locks up when typing into a new tab's address bar. Still using Firefox (55) as the daily driver even though I have to kill it about 8 times a day. FF 57 does fix the need to kill Firefox but then a couple of the plugins I use are not supported anymore.