High res FLAC takes forever to save

Hi,

Many, not all, high resolution FLACs takes forever to save (20 minutes maybe for ten songs). Normally it takes about a couple of seconds, why is that?

Perhaps you have other software running that is interested in the audio files and tries to read them and therefore blocks them. All these programs then struggle to have access to the files.
See if closing a Windows Explorer window or WMP helps.