Safari makes os freeze
You can try the following:

In Preferences (cmnd+,)

Privacy:


Check: Allow from websites I visit.
Remove all website data..
Prompt for each website one time only
Ask websites not to track me


Notifications:

Remove all

Extensions:

Disable them all for now.

Search:

Untick all and only tick: Enable quick website search



Quit (cmnd+Q) and re-open the app. Let us know if it happens again? :)