Rhino for Mac 6 very slow when copy/pasting

I updated to Rhino 6 for Mac this week. Copy/pasting even small elements like polylines from other files takes sometimes up to 30 seconds or 1 minute. Is it because I updated to Mac OS 10.14 recently (had similar APFS problems with ArchiCAD)? Or because I copy/paste from files in Rhino 5 format to Rhino 6?

Thanks in advance