Just to add to this:
There seems to be an issue with some (but not all) new Dell laptops that use a version of the Realtech audio driver and NVDA.
As stated below, there’s a memory leak with the Windows Audio Device Graph Isolation (audiodg.exe) service. When using NVDA, especially for long periods of time, this service eats all available ram and then starts gobbling up virtual memory as well until the device blue screens. This is limited to when NVDA speaks, my testing has revealed that if you leave NVDA silent for a while, the memory slowly comes back down again. This leak also doesn’t happen when other audio is playing so it seems to be a problem with the way NVDA uses this service. But if you’re using one of these effected laptops in a 9 til 5 job, over a few hours, the machine would become slower and slower.
A temporary fix for this is to find the audio driver in use in the device manager from hardware and sound, navigate to the sounds video and game controllers category and update the audio driver. Instead of searching for updates on the internet automatically, choose the manual option and select the button that will allow the user to choose a driver from a compatible list of drivers in the same category. Usually there will only be two drivers in this list, the current Realtech driver and the default Windows 10 driver which is called HD Audio from Microsoft. Click this driver to update and the audio on the machine will stop. Restart the laptop to begin using the new updated driver. Using this HD Audio driver, the issue is no longer present.
I’m not saying NVDA is at fault here because I don’t know enough about this yet. It could be that the driver is the culprit, and NVDA is doing things correctly but the driver is not handling NVDA very well.
So far I’ve tested this on Dell Inspiron laptops from the 570 range and above, from Windows 10 1809 and above and NVDA 2019.1 and above.
Hope this helps.