I'd like to report that this is also the case on my set-up with 3700X + 2080Ti on Windows 10. Average load is about 2%, although there're indeed 'pikes' of loads in GPU-Z's 'Sensors' tab. However, GPU tasks are indeed finished much faster than CPU-only tasks.

This is very different from behaviours of GPUgrid or Folding@Home. When doing GPUgrid WUs, often the CUDA of the Nvidia card will maintain an average load above 90%.

The benefit of WCG's GPU task behaviours now is that my system is a lot cooler than when crunching GPUgrid tasks. But I do wonder if WCG is using our GPUs' most capacity at the moment.