Content.Load hanging for several seconds on Texture2D assets

My DesktopGL project has a persistent, irregular problem on my development laptop (Windows 10, standalone nvidia geforce graphics card with up-to-date graphics drivers): Content.Load will, when performed on a texture asset of any size, take a minimum of around 4.2 seconds to complete (rarely deviating by more than a 10th of a second). While it is waiting the program won’t utilize any CPU.

The specific line of code it hangs on is GL.Finish() in PlatformSetData(), within Texture2D.OpenGL.cs.

I’ve experienced this error in both the master and develop branches of the program. The error is extremely irregular: sometimes it will appear and I will spend the entire day vainly restarting my computer, re-installing Monogame and VS2015, updating graphics drivers, and generally doing everything I can think of to fix it, while other days it will never appear and I’ll be able to work without any problem. This has made me wonder if it’s something to do with power saving features (I do most of my work on the train, without access to a power outlet) or perhaps a Windows software update, but so far I’ve been unable to find any sort of pattern.

I would appreciate any help or expertise anyone could provide: I’ve had weeks of dealing with this problem on and off without success.