Here's a very useful plugin for devs, straight from the man Dark AleX himself. It's a plugin that measures the PSP's speed when reading ISOs and UMDs. It's what DaX uses to compare the speeds between drivers.

Note, devs, this only works for the PSP Slim as it uses the Slim's extended memory. Dark AleX also has a couple of notes you should pay attention to:

Instructions: copy to root and run an iso/umd. The plugin will automatically log the umd driver read petitions in RAM. Whenever you want the log to end, press L R in the game and the log will be written to ms0:/drivers.txt.

Caution: if you log an umd or an iso in normal mode (with umd required), DO NOT USE slim cache.

When comparing two drivers.txt, make sure you compare lines that are equal (except in time).

Don't forget to disable the plugin when you have finished to use it, as it may break some homebrews.

Download: ISO/UMD speed measurer