My laptop has an internal modem I rarely use. Currently it's one of those moments. It is a so-called winmodem that is no real modem, but just a sound device with a splittet driver: An in-kernel alsa one (free) and a proprietary daemon emulating a modem.

I wondered why some tasks that have nothing to do with network were slow as hell. Now, I knew that it just emulates, but I never thought of that:

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND

30458 root      RT  -6  4384 4384 3588 S 17.3  0.9   8:37.33 slmodemd