90 will darken the wort, called a Malliard reaction and give a more malty flavor. Not something you want in a Pilsner. It also gets better hop isomerization giving you better bittering.
With extract you can actually boil the hops by themselves then add the extract at the end for a short boil so it does not darken. I did one last year that I never even got the extract up to a boil after 60 with just the hops and steeped specialty grains. Turned out great.