If you have four lookup tables in the workflow. How do you troubleshoot to improve

There r many ways to improve the mapping which has multiple lookups.
1) we can create an index for the lookup table if we have permissions(staging area).
2) divide the lookup mapping into two (a) dedicate one for insert means: source - target,, these r new rows . only the new rows will come to mapping and the process will be fast . (b) dedicate the second one to update : source=target,, these r existing rows. only the rows which exists allready will come into the mapping.
3)we can increase the chache size of the lookup.