Advice on underperformers

I have a relatively new nurse at my clinic who is struggling to pick things up. She has been here since mid-June. She is very detail oriented, which is good, and has a good memory for new information but she is SLOW. It takes her a while to incorporate new things into her workflow, she often focuses on the wrong thing, and also just moves slowly. There is absolutely no lighting a fire under her to speed things up and she is needing consistent reminders to do pretty simple things, like speaking up to repeat back orders or concur in a time out. What she does she does well, but she has been in orientation longer than normal and I don't see her ever picking up the speed. We are a clinic, but we also do procedures and she is drastically holding up the procedure day. She is only doing half of her job so far- haven't even started to add the other half into her training because she is so slow with what she is currently doing. I have the capacity to let her go, but there needs to be a clear-cut reason that she is failing at her new job, not meeting the standards, but speed of practice isn't a justifiable reason. I'd love any advice on how to deal with this or get this nurse up to speed.