This issue is quite common. If we use Windows on high resolution displays then DPI should be at 120, 144 (125% and 150% respectively) or even higher. By default, it makes some icons on notification area look distorted. Windows 10 system icons like Action Center, Volume, Network etc. look as they should but almost all 3rd party icons are terrible. And it doesn’t matter whether application is high DPI aware or not. Even if applications have appropriate high resolution icons, Windows make them look distorted anyway. To ensure you may place latest versions of Firefox or uTorrent (these checked personally) to notification area and see how their icons look at 150% scaling setting; fuzzy obviously. Then just set it to 100% and switch back to 150%. Now they are scaled correctly and look crisp at 144 DPI. But as soon as you reopen applications, windows make their icons ugly again. It makes me think that there is something wrong with Windows scaling method not icons or 3rd party applications like many threads say. And I would really like to find solution and make Windows 10 desktop look correct on hi-res display. I had the same issue with Windows 7 before and resolved it but I don’t remember how unfortunately. I think I modified some "Size" values in HKEY_CURRENT_USER\Control Panel\Appearance\New Schemes\Current Settings SaveAll\Sizes\0 But I don’t have Windows 7 installed to check at the moment and Windows 10 HKEY_CURRENT_USER\Control Panel\Appearance\New Schemes\ registry key is empty. If anyone knows where these settings are located in Windows 10, please let know. I mean scaling settings for notification icons or their size options. Simple experiment with DPI switching confirms that problem is related to Windows and its scaling algorithm, not applications or their icons. I want to understand what exactly prevents Windows from picking appropriate high resolution icons or scaling them correctly considering that necessary icons are available and OS actually can do things right, but some settings have to be modified first obviously. I also think this information would pretty be useful for many.
Just in case if anyone interested, mentioned issue have been partially fixed in Bulid 14393 (Anniversary Update / RS1) finally. Some notification area icons are still blurred, but look way better than ever before on high DPI.