The reality of most of programming I've done is that in 98% of cases you deal with data structures that are sufficiently small for performance not to matter muc

The reality of most of programming I've done is that in 98% of cases you deal with data structures that are sufficiently small for performance not to matter much on modern hardware. If you do need to deal with data structures that are quite large (i.e., take GBs of memory), perhaps PHP is not the right language.