1-Avoid if condition when load data from data source
2-Don't put more than one where condition when load data directly from data source
3-Put condition checking or If condition after Table Resident
4-Avoid left join and Right join better to use Left keep and Right keep its faster as compare to Left and Right join
5-If you have multiple condition checking at the time of data load so try to avoid if function,you can also use pick function with wildmatch/match doing same things with faster processing .
6-Try to use mapping table and applymap in your script its faster than join.
7-Comments and exclude field which are not in used.
I hope above point is help you.