Just an another PS2 LAG complaint

Getting lag these days on ps2 , i'd like to know why exactly , and if SE is going to fix it and Why if they won'T....

I'm in bostenieux oubliette and whenever i initiate combat it start drasticlly lagging or seems like i have lots less fps or something.
could this be a hdd problem ?

PS2 has a very low amount of RAM(128 MB, and a small amount of Video RAM) and the application has grown to need all of it (possibly more) causing it to have issues.