Maybe along the coastal areas, quicker storms mean less destruction....and the more inland, the greater destruction.
But I was thinking that a slower storm also allows a tornado to build to a large funnel and, therefore, create greater damage.
(But seeing as how I have never once lived in an area where there are frequent tornadoes (much less seen one), I profess my utter ignorance as to anything about them, except for what I read about them from experts or anecdotal commentary from others.)
The very best thing to have is a weather radio,,,(local)
I like NWS radar to see for myself...