I'm an immigrant and moved here when I was 9. My parents always spoke in a different language growing up. I personally had a hard time with certain vocabulary that I never picked up and that maybe I otherwise would have if I had native English-speaking parents. This definitely slows you down when reading problems as you're only gathering about 3/4 of the problem at times. This is probably an outlier, but just thought I'd share my point of view here.