Fast video cutter / joiner - not final cut pro ?

[video newbie!]

Hello,

I'm a video newbie. Here's my noob question: I sometimes have
downloaded video files which I want to cut in (avi, mpeg, wmv,
typical) and sometimes I want to assemble small pieces of those files:
avi, mpeg, wmv etc...

I tried Final Cut Pro, however I think it is slow. I'm looking for a
very fast video cutter / joiner. I tried something on windows:
easympeg but prefer something for mac. Easympeg also is very fast. Why
does people pay so much for professional programs, Final Cut etc when
they're slower?