Optimization

What's your style. Do you constantly think about performance and put grate effort to make your code as fast as possible or do you just make it work and sort out performance issues when they bite? Somewhere between? Do you profile your code or relay on your knowledge?

Just thinking. For example, I need a relatively simple template engine, I could easily implement a high performance version in 100 - 150 lines of code, or I could just use regular expressions and get it around 50 lines..

>>4
Yes, readability is another important factor. Usually slower, but simpler and more flexible code is preferable over faster, but harder to understand and modify.

But how are you "somewhere between"? You write your code to be as simple as possible, solving performance issues only later.