I just built a fresh profile. In about;config, to widen the tabs, I changed browser.tabs.tabMinWidth to 175 With that change, the tabs wheel scrolls too fast, too much tab scroll horizontal movement with each wheel rotation click. It was working fine in my older profile. I believe it is also about;config setting. I thought I had it written down, but I can't find it. I tried changing "mousewheel.default.delta_multiplier_y" from 100 to 20, and while it helped with the tab bar, it also slowed the the vertical page scroll speed to a crawl. To test, I replaced the prefs.js file with one from an older profile where it was working the way I wanted, and while it messed up some things on my toolbar, the tab bar scrolling and page scrolling were the changes i was looking for. I tried searching thru prefs.js, but I didn't recognize the setting I was looking for.