Just in case anyone else is following this, since my Cubase 10.5 loading time became really long after removing AVAST antivirus and depending only on Windows Defender I noticed the lag was in loading East-West’s libraries (mainly). Once I excluded those folders in Windows Defender my load times were back to normal and very fast - possibly quicker than when I was using AVAST. peakae’s suggestions above were a big help and so far the audio glitchiness in Cubase 10.5 is gone - probably caused by AVAST. Onward!