You're not wrong! Some releases (and not just Ubuntu), it does feel like some distros are inching towards their "Windows Vista" moment, where UI aspects slow some things down...But, i think i tend to not get impacted by this since I often use KDE or XFCE....which is not to say that these are perfect nor the lightest-weights either....simply that, i know what you mean, but it doesn't tend to hit me much. Oh, and MX Linux i haven't touched in a long time, but yeah it used to fly and be super snappy back when i had used it!