MySQL performance DELETE or UPDATE?

Question

I have a MyISAM table with more than 10^7 rows. When adding data to it, I have to update ~10 rows at the end. Is it faster to delete them and then insert the new ones, or is it

Answer 1

Rather than deleting or updating data for the sake of performance, I would consider partitioning.

http://dev.mysql.com/doc/refman/5.1/en/partitioning-range.html

This will allow you to retain the data historically and not degrade performance.