SQL Server Express Freezes for a couple minutes
There is couple of important point missed 

Please check whether Auto Close option is set to true for database. I have seen lots of similar issue where Auto close option was culprit.

Is OS resifing on Virtual machine or Physical ?. If its is virtual look for any VM snapshot backup happeing this might also cause freezing.

Other thing can be, do you have backup taken for  database using third party tool/windows native backup  if so these tools freeze data files for couple of sec to sync metadata and take consistent backup.And you can see VIRTUAL_DEVICE in errorlog when you specifically look ta backup information in it. 

Hope this helps