Response time Microsoft Edge

The calendar plugin works well in all browsers (Firefox, Chrome, etc.), only Microsoft Edge reacts very(!) slowly, for example when I activate or deactivate a calendar view. The development tool shows that the servers response time is OK. Does anybody know about this problem? Could this be due to synchronization via CalDAV?

MS Edge Version: 42.17134.1.0
Nextcloud Version:
Calendar Version: 1.6.4

Edge is not a browser * SCNR *