Add a VBA Property for ProtectSheet / UnprotectSheet that selects hash method
See the thread: https://answers.microsoft.com/en-us/msoffice/forum/msofficeexcel-msoother/excel-2013-is-very-slow-in-loading-large-workbooks/3dc258b1-0d9b-492c-8ab8-2ba1df26fc7e. Be sure to read my post: DennisAd replied on February 26, 2017.
1. SHA-512 hash for Worksheet Protection makes VBA that turns protection on/off really slow
2. There is no additional security provided by SHA-512, since the worksheet info is stored in-the-clear on disk.
3. All the code to support older (FASTER) methods is still there.
Details in the thread,