Exactly this. The "Memory" tab in activity monitor is next to useless. It doesn't give you any idea how much of that memory is shared, exclusive to the processe

Exactly this. The "Memory" tab in activity monitor is next to useless. It doesn't give you any idea how much of that memory is shared, exclusive to the processes, paged out, etc. Each of those processes is using some fraction of the amount displayed in the 'Memory' column.