Hello Carolyn,
I used to use my MBP 13" for Revit since 4 years.
of course using Boot Camp Assistant.
the performers that MBP gave me was good, you can model and navigate over your project smoothly.
but when you but furniture in entire project you will face some lags.
you can render still images easily, but rendering a walkthrough is horrible.
last year i upgrade my ram and found some improvement, but its not what i expect.
i will attache my MacBook Pro spec.