IPSW download speed drops by half when UTM window loses focus

**Describe the issue**
If the UTM window loses focus while downloading a macOS VM IPSW image, the download speed drops to about half the speed after one minute. If UTM gains back focus, the download speed gets normal again. The issue was already present in UTM v3, however back then I thought it was just a thing with my internet connection. I now ruled that out, since it's happening every time and the speed drop is very consistent. In the image you can see the download speed (blue). The left and right ends are during focus loss, the middle is while the window is having focus.

**Configuration**
* UTM Version: 4.0.9 (68)
* macOS Version: macOS 13.0
* Mac Chip: M1 Pro