Looking at some screenshots, it has a fancy appearance, probably it's using some hardware accelerated graphics api (D2D for example) do draw its window and controls. Ergo it does use the GPU.
However, if the issue remains when this application is minimized/hidden, it suggests it doesn't release resources as it should and still holds on to the graphics api (and the GPU) for no reason.
I'd open it with the dependency walker and see what api it uses. Running a profiling on it would give some insight as well. Then I'd have something to contoct Logitech support with.
CPU: AMD Phenom II X4 810 @ 3120MHz | RAM: Kingmax 2x2GB DDR2 800 @ 833MHz| MoBo: MSI K9A2 CF v1.0 (BIOS: 1.D)| GPU: Asus HD 6850 1024MB (DirectCu) @ 835/1135MHz | Display: L24FHD | PSU: PC Power & Cooling Silencer 750 Quad | OS: MS Windows 3.11 Pro x64