@casino Black/white lists control whether the sites are blocked. When a site is blocked, it’s never available.
Calendars control when a site is available (for sites that are not blocked). When you put google.com on a calendar with no time allocation, it is equivalent to putting google.com on a black list. However, there are some differences:
If google.com is in the black list, you can bypass the blocking for subdomains such as news.google.com, mail.google.com by putting them in the white list.
If google.com is blocked by a calendar, you need to create a new calendar with open time slots for the subdomains such as news.google.com, mail.google.com.
The page slowdown is a bug. Thanks for bringing it up. It will be fixed in the next update.