You really need configure ifplugd to only control the interfaces you have/want/need. Also, wireless interfaces are notorious system hogs when they are out of range, or at the limit of the range of an AP. As an example, whenever I boot to Windows XP for some gaming, I find that it is totally unusable way beyond the point when everything has loaded and right up to the moment when the "WiFi is not connected" popup shows. At this exact point, the CPU use drops from aprox. 100% to the usual 1 to 2%. The first time I figured out that the wifi was a hog was while trying to work at the limit of an outdoors AP at a sugar plant, when the realtime comms server program I was developing kept delaying the log scrollbox every second or so and then catching up! Finally figured that it all coincided with the wifi dropping connection and trying to reestablish it again. Since then, I tend to use ifplugd only for my wired ethernet and controlling the wifi manually, something I wish I could (as easily) do for Windows too.