Fast foward seeking takes some time

I was watching [MCE-F] Ragnarok The Animation - 21.avi decided to open it in virtualdub then after exploring I tried to quiet while dubbing, but it said "don't do it or the avi may broke" so I said no, then I fast foward and backward the file quickly (maybe too quickly? to see if it was fine, but after that, I tried to play the avi again on WM and it shows "Broken B frame error" ,etc so I decided to reencode it using virtualdub and the xvid compressor, but now seeking times is slow altough for some parts is quick but most of the time the player keeps the last frame static, while already playing the sound from another range, you know when you fast foward it, it may take some time but this is boring I waited 30sec and nothing, so please help me up, to improve seeking times.