I can help with the missing SOC error when you start X.
I run the 2.4.26 kernel. It looks like this new version of X needs ipv6 to be running. So, to eliminate that 'nag' error (X still ran without ipv6 but I was only testing from the local consol, no telnet in), I had to add:
to the rc.modules file to get it to load at boot.
If you're running the 2.6.x kernel you may not have to add it (I believe the ipv6 module may be compiled into it, but ... ? ).
Speed, can't help with yet... just installed slack 10 today and still checking things..