The problem. The PHP implementation [of the IP2C library] is a lot slower. Embarrassingly slower. Without any caching the Java version is able to do ~6000 queries per second. The PHP counterpart can push through ~850 queries. The implementations are the same. The stats provided by the author of the library are 8000 vs 1200. So about the same as my measurements.

He details the script, showing what parts the script is taking up the most time on. A large part of the execution is tied up in IO and the fseek/fread and readShort/readInt functions take up a good chunk.

He even tries removing the functions and making things a bit more streamlined. This helps, but still lags behind its Java brother. Check out the post for more statistics comparing the two.