Is your KDE slooooow? Check your loopback interface

While digging Debian Qt-KDE's bugs, it has become more common to find people reporting that their KDE is very slow. Most of the time (if not every time) it turns out that the loopback interface is down. Sometimes the user did something wrong, sometimes some network manager, but the end result is the same: KDE is terribly slow.

A user filled a bug upstream to ask for a dialogue in KDE that warns the user about this fact. Let's hope it get's implemented :-)

OK, so, how do I check that my lo interface is up?

You can simply run:

$ /sbin/ifconfig 

eth0      Link encap:Ethernet  HWaddr 00:1f:c6:ba:70:f3  

         

lo        Link encap:Local Loopback  

          inet addr:127.0.0.1  Mask:255.0.0.0

          inet6 addr: ::1/128 Scope:Host

          UP LOOPBACK RUNNING  MTU:16436  Metric:1

          RX packets:1807 errors:0 dropped:0 overruns:0 frame:0

          TX packets:1807 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0 

          RX bytes:494525 (482.9 KiB)  TX bytes:494525 (482.9 KiB)

The last entry "lo" tells us that the interface is up.

In Debian, the file /etc/network/interfaces should have something like:

# The loopback network interface

auto lo

iface lo inet loopback

So, next time you find a KDE session is slow, you know what to do ;-)