> How does httrack behave performance wise if I start 50 
> httrack's with 1 url each compared to to starting 1 
httrack 
> with those 50 url's in a list given to httrack.

It won't give the same result: 50 URLs in a single project 
will "share" the same namespace, and therefore cross-links 
between these domains will work.

For performances, 50 different projects will be faster 
overall, but it mainly depends on what you are trying to do.