alexintokyo LOL, I can imagine how slow it was getting. I have a bad habit of accumulating around 40 to 50 tabs loaded up, and that is in a single instance of FireFox. When it begins slowing down (at around 50 tabs) I know that it's hitting the system's 32GB of RAM pretty hard, and I'll close a bunch of tabs to lighten the load.
You must have been customizing your desktop, i.e. by deleting Mate's lower (bottom of the screen) Panel bar. That's the one, in the default Mate' configuration, that contains the Window List and Workspace Switcher. In customizing Mate' the first thing I do is delete the bottom Panel bar too, then move the top Panel bar to the bottom of the screen, or to one side, and add back those handy items (Window List and Workspace Switcher).
While I'm on a roll I'll share some more Mate customization's: My main system is indoors in subdued lighting, and I've grown fond of making use of dark themes. They not only look classy but they make computing much easier on one's eyes, by cutting out all the glaring white backgrounds that are like a spotlight shining directly into one's face. There is a really nice GTK theme available in the Software Station that is slated for the XFCE DE, but it works very nicely for Mate too, and looks much better than the dark theme included with Mate.
The theme I'm referring to is in the 'greybird-theme' package, and once installed 'Greybird-dark' will be found listed in Mate's themes (i.e. System, Preferences, Look and Feel, Appearance - Theme tab, Greybird-dark). And in the Customize area I'll change the Icons (to Mate) and the mouse pointer (to the white arrow). It's like having a brand new desktop, very refreshing.
Next is to tweak FireFox by using an add-on extension to cut the glaring white backgrounds common to the majority of websites I frequent. My favorite extension for this is 'Dark Reader'.
HTH, Byron
