This list shows which scripting and internal game functions use CGM Buffer. Extensive use of them may cause CGM Buffer Overflow.

Code:
damagepuff
huddraw_shader (ihuddraw_shader)
huddraw_align (ihuddraw_align)
huddraw_rect (ihuddraw_rect)
huddraw_color (ihuddraw_color)
huddraw_alpha (ihuddraw_alpha)
huddraw_string (ihuddraw_string)
huddraw_font (ihuddraw_font)
damage
_barrel_think
killed
pain
dmmessage
explosioneffect
BulletAttack (internal function executed during weapon fireing)
Often function that cause this are: all huddraw and ihuddraw function. Keep in mind that dmmessage could cause this too so mods that spam players with console messages could also be a source of the overflow.