FWIW - After a bit of experimenting I was able to get a nice clean cut on some rubberized cork gasket material both 1/16" and 1/8" thick. I used double sided tape to hold it down. I thought I’d share my settings in case anyone else comes across a need for a hard to find replacement gasket.
1/8" 2-flute straight cut bit, HSS
max RPM on my Dewalt 611 router, 27000 RPM
800 mm/m feed
Conventional cut, not climb cut
1 pass, full depth