I have 2 linksys e900's
I was noticing signal strength dropping whenever there was around 6 devices using the router, also the gui would slow.
while trying to regain some speed by disabling QOS, logging and messing with stuff, I noticed the power adapter is only 0.5a so I tried an old 1.2a adapter and now it seams to fly, now QOS and signal strength are great
If anyone is bored please test this out so i know its not just snake oil, this might also benefit other E series routers