Firmware dd-wrt on asus

I tryed every version of dd-wrt firmware on a asus rt-n10 plus and i noticed that after some minutes/hours it starts to slowdown. On those slowdowns i get several packet loss and 200ms+ pings. I have tryed the latest brainslayer´s builds with the same bad results. I don´t know if this aplies to all asus routers but i reinstaled the original firmware and all went smoothly again(too bad the base firmware has no extra features at all ). I have to say that i mainly tested it on repeater mode.