I used to stutter less in my non-native language. Because I was living abroad for the first time. It was fun, I was a brand new person nobody knew me there. I could be ME, with a new personality. I didn't care as much what people think so I mostly didn't stutter. The moment I came back to my hometown and talked to distant friends from school that I always complexed about, no matter what, I would stutter like crazy. Even if I would rationally tell myself "wtf buddy, you shouldn't have anxiety towards these people anymore, you have the life, you're happy what's the fuss!". But that still wouldn't cut it. Then one day that foreign language became my work language and I started feeling anxious speaking to people I highly respect I work, and I started stuttering the hell out of myself again. So I think, in my experience, it's not about the language but the stress I put myself into. I believe that it is stress everybody has, I'm not special in this regard. Everybody can be nervous in life but for me it translates into stuttering, so I got to pay extra attention to chilling myself out.