I have a project involve a highload (image,api), I still finding the best solution. I know phalcon is very fast but what if vs custom php code from scratch ? Is it still faster or lower or the same in speed?
I think you can create a couple of raw scripts that outperform any PHP framework, however, as time passes and the application grows, raw scripts are difficult to maintain increasing the number of bugs and bringing many problems to the table. This is the reason why frameworks do exist, you can find good frameworks that provide you good performance while keeping your application structured and more maintenable.
You just cannot compare RAW PHP vs. anything else. That is like a starting point, and if you add any overhead (with any fw) you'll get slower results, obviously. So in short - raw PHP is by default faster, in case you really need to do something so speed intensive... but then I'd suggest you to grab a really fast CPU.... PHP just likes raw CPU power since it is single threaded enviroment... 4500 MHz and you'll fly with it :)