bad loser
As a paying member your opponent is allowed to use vacation time and avoid losing by time in daily games. This time is not infinite (they have 4 weeks left). If you feel that they are deliberately dragging out a hopelessly lost game then you have the option to report them for stalling. I suggest you don't bother and just wait patiently for your win to come.
If you are close enough to an endgame, you can use the conditional moves button to just play all his available moves, and let the game play itself out.
I think it is normal behavior to stop and think about your game if you are in a losing position, so I can understand why someone may start playing slower, but if you feel they are being unreasonable, then report them for stalling / vacation abuse.
