Often the spinning wheel is a sign that virtual memory is working overtime. Do not know how much memory is installed so hard to say if more memory will be a cure or if 70% is too high an allotment.
Also with any Adobe program make sure there is a lot of free disk space for the scratch files.
You could also go into preferences and reduce the number of undoes available. Yoy will have to let experience tell you how many undoes you really need. I can usually make do at 20 but some projects need are more complex.
I have also found that with 20MB and bigger files that I like to have a maximum of four images open at one time. My system is a lot older than yours and you should be able to handle more images than that with ease.
Also with any Adobe program make sure there is a lot of free disk space for the scratch files.
You could also go into preferences and reduce the number of undoes available. Yoy will have to let experience tell you how many undoes you really need. I can usually make do at 20 but some projects need are more complex.
I have also found that with 20MB and bigger files that I like to have a maximum of four images open at one time. My system is a lot older than yours and you should be able to handle more images than that with ease.
