Are left joins more efficient?

Hello, I program for a website that gets massive loads of traffic. Optimisation has become an important issue lately. At the moment, all queries on the website follow the same format when joining tables: SELECT * FROM table1,table2 WHERE table1.id=table2.id; My question is, would this format be more efficient? SELECT * FROM table1 LEFT JOIN table2 ON table1.id=table2.id; Over the last couple of years I have read and heard two different answers. Years ago it was said that doing Left Joins are faster and more efficient. But with recent updates to MySQL I have read that both queries are broken down and optimised the same way by MySQL. Any thoughts? I havn't come across any comparisons on the web, so any answers would be appreciated. (couldn't find any mysql specific groups so i'm posting in the next best thing!) Thanks -Dennis