Also, from moment to moment, results are often different between 2 consecutive runs both using su (or 2 both using sudo). This is especially true if you run ps_mem.py (or ps auxBYOB) while a web browser is running (due to garbage collection and memory management being performed within the browser process).
Not related to the subject at hand in the last posts (but related to the OP)
Don’t forget to UPDATE and UPGRADE your system!
Since the last upgrade I noticed that I could not start synaptic from the start menu, nor from my application finder. I tried the yad-updater script, it refused to run. I guessed it was some kind of problem with gksu, manually updated and upgraded from the terminal- and success! Synaptic is starting, yad-updater too!