Hi Rainer,
First you need to consider that some of your site is "public" (and analytics for that is good) and some is behind a login (and analytics there is pretty useless.)
Also - it's only useful at the "page" level, so it doesn't work on popups, or content-body refreshes or anything like that.
>> Does it slow down the show?
yes, of course.
>> Do You put google´s code on every procedure?
up to you I guess. It can be added globally (via a global .js file) but it depends on what you are trying to do.
Cheers
Bruce