- Out of the box, PHP tends to execute more slowly than assembly, C, and other compiled languages
- PHP is loosely typed. For developers of all skill levels, this allows room for unexpected behavior due to programmer error that many other languages might not permit. [Of course, few if any languages can protect from developer error!]
- There are many ways to do one thing, and many cases where a function has ambiguous handling due to legacy support or PHP development history.