I did some writing about two weeks back that included me rambling on that... we can probably pick or even draft up a question on which I can talk about start small, measure, and scale well.
There is no shortage of folks running around the world trying to create the next Facebook. They crop up regularly on Serverfault asking what it takes to handle 10,000 connections per second for their next big idea website. I don’t have any good examples to reference because they’re bad questions; bad questions are closed and deleted. What those questions would show is a common problem in the world of system administration: the basic lesson unlearned.
There are an ample supply of questions on Serverfault consisting of, “Is this faster or why is that slower, etc.” The answer to those questions in most cases is, “we don’t know you hardware, measure it and find out.” A computer consists of multiple finite resources and in most cases bottlenecks on one of those resources. Most of the time that resource limitation is available memory, processor speed, or disk speed. There are others besides the big three, but the answer is always to measure, locate, and alleviate in a cost-effective way.
Thus, when it comes to adding services don’t tell me SSL is too slow, but rather tell me what it limits you to for speed. A good example I came across this past week was figuring out the cost of / most cost effective way to provide SSL on EC2. I was impressed that the asker had done a lot of homework before and took a look at comparable benchmarks to determine that things “didn’t feel right.” I find many questions where this task isn’t completed. So, whenever you start, consider if $whatever is worth the cost, and do it with a “de minimis” in mind — don’t calculate the small stuff, but if a few thousand in hardware or time is on the line, think it out. Sometimes cost isn’t the only factor, but be aware of it.
Finally, do the default to start. What works 90% of the time for 90% of of folks will probably work for you, or at least be a good starting point to compare against. Optimizing for a target before you’ve been able to measure it is, thanks to the laws of thermodynamics, comparable in efficiency to lighting money on fire. Both will generate heat, but I wouldn’t count on much more besides some ash and a waste of resources.