Mac OS X 10.6
When multiple users logon and launch some applications at the same time, say Photoshop or Adobe Creative Suite 5. Will Mac OS utilize memory smart enough by letting both instance of applications using same chunk of memory? Thanks.
In general, no. When two different users launch a program, they must run as two different processes owned by the individual users. To share memory between these two instances could easily become a security breach as one user could change the memory being used by another user.
In theory the superuser could get around this, but apps must be written not to assume superuser privileges unless there's an explicit need for them.