I'd like to endorse what others have said about temp tables.

I use CTEs a lot, and often they make the query both more legible and faster. But sometimes they seem to overload the optimiser and result in a very slow plan. I have speeded up some UPDATEs from minutes to seconds by splitting them into a SELECT INTO a temp table then an UPDATE FROM a join to that table, compared to my original code that used WITH cte ... UPDATE.