I was curious why does 'pacman -Q' operations took longer than 'apt' counterparts. It seems that the local pacman databases are just subdirectories with text files (desc, files) and gzipped text (mtree). No wonder why local pacman databases tend to slow down over time and need to be optimized periodically.
For long term pacman development road map, it would be better to use single sql based database for tracking locally installed packages instead of keeping directories of every installed packages.
This would provide faster access for local database as sql databases are optimized for fast access.
optimisation ideas to the pacman database are (nearly) as old as this distribution, but none ever really convinced many. if you go back through the archives of the mailinglists and forums (as well as the outer parts of the interwebs) you will find many similar ideas. i specifically remember an approach to read the database once on startup, and store it in a ramfs. hat its disadvantages as well… for all actions regarding the database, i strongly advise you to do a full backup of the whole database before tinkering with it. my advice: get a SSD drive for your system, that makes the pacman database lightning fast, but your data is as safe as can be. georg