I realise this may be a newbie 101 question so please bear with me.
I've noticed that my slowest queries, which take minutes to return 2K + nodes take a few seconds if I'm only counting the results. Is this due to the memory overhead of loading the nodes into RAM? I assumed the times would be similar - that the time would be spent in the plan execution - not in returning the results? I'd be grateful to know what's the general cause for this difference.
Btw, I've been reading the pinned articles in the meantime on tuning (many thanks).
Thanks in advance