With select into

When you create and populate temporary tables in tempdb, use the select into command, rather than create table and insert...select, whenever possible. The select into/bulkcopy database option is turned on by default in tempdb to enable this behavior.

select into operations are faster because they are only minimally logged. Only the allocation of data pages is tracked, not the actual changes for each data row. Each data insert in an insert...select query is fully logged, resulting in more overhead.