This is just an informal write-up of my private/spare-time fiddling with pdfeTeX (it's for fun).
This patch unfortunately does not give the hoped speed gain over the unpatched version. There is no speed gain at all. Which simply means, that pdfeTeX does not spend a big share of time in hashing, ok. Anyway, this experiment was good for looking a little into some pdfeTeX internals, e. g. how format dumping and undumping works.
A snapshot of the patch, which is against pdfeTeX, version (Web2C 7.5.2) 3.14159-1.20a-2.1-rc1, can be downloaded as a gzipped file: tex.ch3.gz.
This page first put online 13 April 2004.