MP Perfomance

Dear Newsgroups,

after building successfully an MP Kernel, I wonder why the performance does
not increase equally.
Services like FTP runs slower compared to an UP Kernel on the same machine.
Also compiling is not really faster. All I can detect is, that the avg load
is the half since it shares on 2 processors.
How can I detect, that 2 processors are running well? 
Where is the advantage of running multi?

Greets de Zafer.