Above you can see I've set my SDRplay to the full 8 MHz of bandwidth. It's tuned to a Volmet upper-sideband weather report and there is no stutter. HDSDR reports only about 50% CPU usage. (Notice how overall usage is not ~100%, like Windows 10 would be?)
Fortunately, I also imaged the drive before going back to XP, so I have a Windows 10 drive image. After a nice break from Windows 10, I have to restore it so I can finish an app I'm working on in Visual Studio.
I restored my Windows 10 backup. Here in Windows 10 I've got HDSDR tuned to some RTTY on lower-sideband and it stutters incessantly. CPU usage is almost 100%. (If you click to zoom in, you can even see a strip of waterfall smear at the top where HDSDR froze.)
But maybe Windows 10 isn't really to blame. Maybe my laptop is just too old to hardware-accelerate all the visual styles, so it has to be done by the CPU. I would like to blame it on the background processes, but HDSDR itself is at nearly 100% CPU, and the overall CPU reading is only marginally higher. A newer computer should be able to run HDSDR with 8 MHz bandwidth without breaking a sweat, but there's no denying XP was a much leaner OS.