Please give me your systematic approach as an oracle/computer expert in this issue :

If you are working in a company and all of the sudden, one or many of the end-users come up to you and say
my computer is too slow what steps normaly you follow to find the bottleneck.

I know there is bunch of different things can involve for instances :

Network traffic in LAN
Application sql out of tune
Operating system memory shortage / swapping / lock
Oracle server intensive operation by other users
Oracle server fragmentation issues
and many ..many more

But I need to know how do you start your investgation, what questions you ask and what you are more suspect for the cause of the problem. If you can give me one real life example that happens to you, I'll appreciate it.