So have no fear, I'll do it!
What makes sense? You want code you can read, yet you also want it to run incredibly fast. Interesting! Well, like any project the first one to market usually gets the worm. So cranking out code (read: code that "works") is typically a developer's (and many times the project managers) first concern. Do we have something out there to start drawing in the cash? Yes. So you've effectively coded for "readability" since we're not optimized. You've gotten your product on the market which is really what your first goal SHOULD be, unless of course there's some ungodly amount of volume that you KNEW of and should have optimized according for it in the first place.
Now, wait a minute...that sounds like common sense. If I'm developing something new that no one knows about, what's the point of optimization? I can just crank stuff out that "works" and polish up that while we gain customers/visitors/whomever. Correct!
On the flipside of the previous paragraph, our (I mean everyone's, not mine personally) good friend with a framework Ezra Zygmuntowicz had an interesting quote a while back where he said "Post-optimization is the route of all hosting bills". In the article I'm extrapolating on, one commenter said if one codes strictly for readability, optimization will come automatically because hardware continues to get faster. The author himself also said "Performance can be optimized at the hardware level", which blew my mind. Why are you even asking for hints on code optimization (for PHP) if you already made up your mind to throw hardware at it? I can't speak for him, but I'm pretty sure you're not going to be replacing your systems with the latest and greatest hardware every 18 months are you? Hmm, Nope!
So what do we need to do?
Well, we've already cranked our code to production, things may or may not be fine with the community accessing it, and I'm sure you've been paying close attention to which aspects of your system need work, help, or simply need to be scrapped and redone. Wait, you haven't? Ok, let's start there.
Pay attention to what your application is doing.
Get a decent logging or monitoring system and pay close attention to the needs of your app. Many times we get so caught up in producing that we never pay close attention to the simple things once it's out in the wild. EVEN MORE TIMES than not, people don't see what applications that may be similar in nature are doing or how they're reacting online to try and investigate why they are having these problems. Chances are, your application will have them too - you cannot assume that just because you wrote the code that it is exempt from bottlenecks. In fact, I'd say the vast majority of the time, you're going to hit the exact same problems as your competitors.
Do your research, if they're a fairly transparent company see what growing pains they were having and try to plan accordingly.
Now that we've addressed the issues surrounding our application AND applications which are similar in nature to ours we can now effectively move into the space where we begin optimizing our code. This is a rather vast term and your focus should (in my opinion) stem from your I/O bottlenecks first before jumping to your code. If all seems well in that area or you simply don't have the funding to do much with it, then sure, you're ready to start optimizing code.
So in essence the life cycle is as follows:
1 - Produce working code that meets your needs.
2 - Analyze how it and other I/O (disk/network/database) are affecting your application.
3 - Attempt to alleviate as much of that I/O overhead as you can within your boundaries (manpower, funding, etc...).
4 - Optimize your code.
I think that will get you through the day. I could be wrong, I flew through this post pretty damn fast. I feel a site optimization post coming soon, so get ready for some more Kool Aid to drink.
