you might wanna try to ask her to stop playing...
then try it
if it dosnt work then ask her to turn off laptop
if still lags try lowering game quality like the other guy said
or you can lower the mouse movement speed.
u could also get a new router and hook up that laptop to the router and use the good one
or just seperate more of a distance
if i help plz thank me =)
it could be your internet speed...or your computers memory close anything that could be using internet,, MSM..inetnet explorer...ect then try or if its your comp try lowering the games texture settings