Stopped reading after the first pointless micro-optimization. With some very rare exceptions, the cost of these kind of optimizations in terms of resulting in hard to maintain and change code are far greater than the cost of bluntly adding more hardware.
I mean seriously, if you're using PHP's OOP functionality but you find yourself having to squeeze out performance by dropping getters and setters on your classes, you should really first take a step back and take a good look at your entire approach.
Those kinds of optimization may be sensible to tighten some critical inner loops of your code. But especially there you should avoid high-level features anyway.
Also, before trying to squeeze out performance that way, you might as well rewrite that part of your code in C, and let the C compiler perform real optimizations.
However, chances are good that you don't even need that, as some intelligent combination of already existing fast PHP functions (implemented in C) usually does the trick.
I mean seriously, if you're using PHP's OOP functionality but you find yourself having to squeeze out performance by dropping getters and setters on your classes, you should really first take a step back and take a good look at your entire approach.