I can't remember what search terms I used - I'd been searching for a while before thinking of this community and I didn't keep a record. Um, "spinning silk" definitely. Probably something about speed of spinning. "Handspinning". Sorry, if that's not good enough I'll have to do all my searching again so I know where I've been.
ETA: On a spinning wheel, not a drop spindle.
ETA2: Thanks, everyone. I'm going to go with her spinning finer wool than she's used to rather than silk - I had no idea how unusual spinning silk would be in the setting. I'd never used a site like this before and I'm amazed at how informative this has been.