A foreign workmate seems so dumb

I have a Japanese workmate who doesn't seem to understand instructions. I don't know why but she needs us to keep repeating whatever we're saying over and over again. It's not that she doesn't understand English because she does, perfectly well I might add. Even other workmates who are not from the states even get pissed at her lack of ability to comprehend. I don't know why she's like that and I'm running out of patience to be honest. And to be clear, I'm not ranting all these because she's a foreign person. I'm saying all these because she's really pissing everyone off. How do we tell her about our issues without insulting her? I'm really desperate for help.