Is the Data Structure Optimized?

When you first start looking at a piece of code that need some performance improvement, do you use any tools to tryto find places where porformance could be improved? There are tools that you can use to check for the hardver efficiency. By just looking at the cod i can guess if it has suffers mostly from det the cash misses or vextorization and so on. We're starting up an online competition in which people will share their knowledge about how to improve software with each other. It's like a contest, but not really, because you need to cooperate with other people and exchange information.