I want to address a few things in that list now that I look at it, too.
Set the maxvalue for your for-loops before and not in the loop.
I don't completely agree with this. I see no problem with the following.
for($i = 0, $toi = count($eyes); $i < $toi; $i++)
Avoid magic like ... __autoload
Nonsense. There's a little trick with __autoload where you place the definitions for classes that are likely to be used in combination with the autoloaded class so that it still works like loading a library of functions via include, but also keeps the awesomeness that is __autoload.
Use full paths in includes and requires, less time spent on resolving the OS paths.
The reason you should do this has more to do with knowing where you are on the filesystem and always using the intended file than it does speed.
If you need to find out the time when the script started executing, $_SERVER['REQUEST_TIME'] is preferred to time()
Be sure to take into consideration the "auto_globals_jit" setting on your server when thinking about this. I'll leave it up to you to figure out what that setting is for.

Turn on apache's mod_deflate
Has absolutely nothing to do with PHP. To say this optimizes PHP is like saying a NASCAR racer is a better driver because his car is 100 pounds lighter than it was before.
A PHP script will be served at least 2-10 times slower than a static HTML page by Apache. Try to use more static HTML pages and fewer scripts.
I can not stress how much I agree with this enough. Most pages that people make with PHP don't change very often.
I actually use a cache folder where I have PHP save a copy of the page using the REQUEST_URI that mod_rewrite ended up turning into a traditional URL before PHP got ahold of the request.
Subsequent requests to that URI use mod_rewrite to check that cache folder and rewrite the URI to any existing static file found in there before turning it over to PHP if it doesn't find anything.
Here's a little bit about
combining that with gzip.mod_gzip which is available as an Apache module compresses your data on the fly and can reduce the data to transfer up to 80%
Same thing I said about mod_deflate. Also, be sure to take a look at the link I posted a second ago.
Strong with this one, the sudo is.