Well if you've run all the utilities suggested & nothing wrong can be found & no there's improvement to LW, then try using the LW 4.1.5 Beta & see if this makes any difference.

Personally I'm a great believer in RAM & believe u can never have too much. Perhaps that's from my experiences with some earlier macs. Still, if you're confident 256 is enough I won't argue with that. But I'd suggest u don't run any other apps initially whilst using LW until some solution can be found.

In any case, go to your Utilities folder & locate & open Activity Monitor after having opened LW. Add up all the individual Real Memory items listed on the right hand side of the Activity Monitor window. Post back what your total is. Also list how much LW uses. This will help us to eliminate memory as an issue.

I'm curious to see if the beta will make a difference. I use both 4.0.4 & 4.1.4 beta.

I just checked my ram usage for LW & it's using over 120 MB ram yet I'm not even dwnlding (someone's uplding.) 2 hrs ago it was using 80 MB. I haven't even done a search since it's been on. (A couple of files did dwnld earlier.)