A workaround has been posted here - many thanks to rawalanche.
With the Fall 2017 Creators Update, Microsoft has introduced some new code which tries to patch exploits in softwares. These patches significantly reduce performance of some functions, and by default they are enabled system-wide. The function GetPixel (which Microsoft stresses in their own documentation, you should never ever use, because it's slow) is affected by one of these exploit preventions, making it further 10 to100 times slower. Annoyingly this is used in the Ribbon bar and some other areas of MFC (Microsoft Foundation Classes)! This is why SDR Console and some other programs suffer with Windows Version 1709.
(Hopefully Microsoft will correct the code in 1709 so applications which use the GetPixel function run as the should.)
Note: If you use another AV software, like for example ESET, then you would naturally assume everything Defender related is disabled, and you would be wrong. If you use Defender, you will be brought to the Windows Defender Security Center straight away, but if you don't, you will end up on a Settings page saying that Windows Defender is not available because it's turned off. Click "Turn on Windows Defender Antivirus" - don't worry, your AV software will disable it again straight away.
Use this information at your own risk, neither SDR-Radio.com nor anyone else accepts any responsibility for anything untoward that may happen.