mouse behavior in new GTK apps under TDE

Greetings . . . I've installed the newest GIMP, 2.10.x, and I've observed and endured a phenomenon that I've previously found in other new Gnome apps running under TDE: functions such as scrolling and slider bars are *very* slow. The mouse pointer moves as quickly as expected, but the scroll/slide pokes along and sometimes comes to a complete halt. Is there a setting someplace that will let me use Gnome apps under TDE and have the mouse work as well as it does in native Gnome? I'm using Ubuntu 18.04 LTS. Thanks in advance. dep Sent with ProtonMail. Because privacy matters.