Quote from Murasaki;1255467:
the lag of a thousand years
lol'd
Yeah, tools should definitely work with no delays for things like that.
But did you take a look at the previously mentioned Efficiency Indicator?
[Image: http://helpx.adobe.com/photoshop/kb/optimize-performance-photoshop-cs4-cs5/_jcr_content/main-pars/img_0.img.png/efficiency.png]
If it goes below 100% when you see lag, then the cause is a lack of RAM. Otherwise, it's caused by a lack of processing power.
From this KB article:
http://helpx.adobe.com/photoshop/kb/optimize-performance-photoshop-cs4-cs5.html
Which also mentions:
Photoshop generally runs faster with more processor cores, although some features take greater advantage of the additional cores than others. There is a law of diminishing returns with multiple processor cores: The more cores you use, the less you get from each additional core. Therefore, Photoshop doesn’t run four times as fast on a computer with 16 processor cores as on a computer with four cores. For most users, the increase in performance that more than six cores provides doesn't justify the increased cost.
So I guess a 6 core build is not unreasonable--particularly when you no longer need to spend $1000+ on just the CPU to get the extra processing power. Might be more power than you need, depending on what you actually do. I dunno.