Preventing GPU-bound application frame rate to drop when window is out of focus

Question

I'm trying to run 2 instances of the same GPU-bound application (OpenPose 1.5.1) on a relatively high-end system and I need each instance to run at the same speed. However, the performance varies greatly whether an instance is in focus or not. Here are the numbers (frame rate) I observed running 2 instances at a time:

• one on focus: ~21fps
• one out of focus: ~4fps
• both out of focus: ~11fps

Here is my configuration:

• OS: Windows 10 64-bit Pro v1803
• CPU: Intel I9-7920X@2.9GHz
• RAM: 64GB
• GPU: Nvidia GeForce RTX 2080Ti
• CUDA 10.1/CUDNN 7.6.3.30
• Nvidia Driver 436.48 (release date 10/01/2019)
• OpenPose 1.5.1
• OpenCV 4.1.1
• python 3.6.8
• Video source: 2 USB cameras, 1920x1080 @ 30fps

Clicking on a window to bring it in focus used to not change its frame rate, but somehow it now does. The previous config I had (that worked) differed from the above setup as follows:

• GPU: Nvidia GeForce GTX 1080Ti
• CUDA 8/CUDNN 7.2.1
• Nvidia Driver 430.xx
• OpenPose 1.4
• OpenCV 3.10

I think the solution might have something to do with the OS or the driver. Is there a way to have both instances run at the same speed regardless of whether they're in focus or not? Thank you in advance!