Question about HDD size and fill

So guys, recently I've managed to almost fullfill my 1TB HDD completely and when the free space became less then 10GB my PS3 went REALLY slow, at the point of being uncapabble of to load any backup that I had copied to GAMES folder. So I've made a HDD Regenerator check (to see if the HDD had any bad block and for my good suprise it has 0 bad blocks) and made a Low Level Format. Then I made a fresh CFW installation from scratch and managed to intall my PKGs. Now everything works great.

My...

Question about HDD size and fill