Embedded or web fonts for my app?

I'm developing a web app. The PR portion of our site that talks up the app uses embedded fonts from Typekit. I'm wondering if I should use these same embedded fonts in the actual app itself too. Does anyone have experience in how much this would slow down the app? In theory, it should slow things down but I'm wondering if it's OK to have this tradeoff if the design is consistent across the site. Anybody have any advice on this issue?