I use nitride coated bits. Seem to cut better and stay sharp longer. Of course, sharp bits work better than worn bits. I use a variable speed drill so am able to try to find the optimium rpm for penetration. I typically start at high rpms and slow down until I can see I have some cutting. Each metal has it's optimium cuttng speed, but I forget where to find the info and how it relates to drilling. I learned about it in machine shop setting up a lathe for metal work. In my experience stainless does take more pressure on the drill bit to penetrate.
2005 Trillium Outback w/ 30" tongue extension
1989 Award 730, 30'
2003 PT Cruiser
1998 K2500 Chevy Silverado 6.5 Turbo Diesel, 4X4, ext cab, short bed