Memory
From Hackepedia
Debugging memory hogs in BSD
To discover which process is using the most memory percentage wise:
# ps aumx | head USER PID %CPU %MEM VSZ RSS TT STAT STARTED TIME COMMAND frankk 64873 0.0 7.9 71352 61644 ?? S 11:17PM 20:07.78 /usr/X11R6/lib/firefox/firefox-bin frankk 607 0.0 7.7 74080 59832 ?? S 4:25PM 6:18.70 /usr/X11R6/lib/thunderbird/thunderbird-bin frankk 583 0.0 7.0 64728 54568 ?? I 4:25PM 17:46.62 /usr/X11R6/lib/firefox/firefox-bin root 561 0.8 3.0 152640 23116 v0 R 4:25PM 10:37.38 X :0 -nolisten tcp (Xorg) frankk 869 0.0 3.7 34332 29036 ?? S 6:10PM 6:13.38 gaim frankk 611 0.0 1.6 16476 12560 ?? S 4:28PM 1:39.09 xchat root 678 0.0 0.5 5604 4000 ?? S 4:54PM 0:05.35 xterm (xterm-static) root 644 0.0 0.5 5512 3916 ?? S 4:35PM 0:14.46 xterm (xterm-static) root 392 0.0 0.3 3460 2332 ?? Ss 4:24PM 0:01.97 sendmail: accepting connections (sendmail)
Two other columns worth noting:
vsz = virtual size in Kbytes (alias vsize)
rss = resident set size
Lookup "KEYWORDS" in the ps Manual for a list of keys you can display.
swap is also an important part of memory that resides on the disk.