PS is slow

[Light]

hi
i've started an huge digital painting today, sized 4800x2400, after painting the colour blocks i've started to smudge some parts but as soon as i started to smudge photoshop started to work so damn slowly, like i clicked to smudge and the result appeared after 20 seconds.
i can't paint in these conditions, so i already tried to clean my hard disk and when i work with PS opened i have 1,5 GB free (i think it's fair) and increased the RAM percentage for PS to use to 75% (from 55%).
After that nothing happened.
So i looked to the file size and it's already 55MB so i resized it to 2400x1200 but still it's taking too long, like 5 seconds, to render the smudge on my screen.
Any helps about that?suggestions?
I have 1gb ram (75% taken by ps) and a quite recent video card and 3,2ghz amd athlon..
thanks in advance

[Smiling Demon]

um basicly i think its your ram... tbh i think most people that do big digis have at least 2gigs of ram.

[Light]

gosh i'll have to buy some :°(

[Kelso]

Mine gets like that when I work at anything over 1280x1024, and I have a gig of RAM.

[Light]

i wasn't expecting that because i already have done photomanipulations over 1500 px format and the psd was like 150mb but i don't know, when i paint it just doesn't work...guess i'll have to resize it a bit once again but i wanted to work very large damn >.<

[Spluff]

Yup, your computer is too slow. You shouldn't need to work at that big of a size anyway, I usually work at double final size.

[Quaggy]

lol, i have a gig and a half and nethin that size screws my speed up.....haha gig and a half weird i kno but i will be buyin a new one soon when am workin agen......lol