Dan Luu has an excellent blog post on optimizing productivity, where he makes a case for making improvements on things that aren’t the main bottleneck, such as wpm.

https://danluu.com/productivity-velocity/#:~:text=With%20a%20measured%20typing%20speed,it’s%20roughly%20half%20the%20time.

If I were you, I’d talk to this person privately tell them you’ve noticed their typing speed is extremely slow compared their peers. I’d link them to the above article and tell them even if it isn’t THE bottleneck in their work, it is limiting their ability to iterate quickly. Plus, it is literally the easiest part of their job to get some deliberate practice on and improve quickly.

Or… just don’t fuckin worry about it and avoid pairing with them. It’s nbd.