I found the solution!!! HEUREKA!!!
I was using only one Layout in the database, which was containing all fields (around 110). For these special searches with the many hits, only six fields are used for displaying the data. I created a special layout for these replies and , voila, it is quick as in FMP 5 or 5.5
Funny, the newer FileMaker apperantly doesn't bother about the used Layout.
Uli