Learn Spanish (Latin America): Se me olvidó que eres igual de rápido que yo.

Both mean "as fast as" and are completely interchangeable. The structure you are practicing here is igual de + [adjective] + que. Just be careful not to mix the two structures together: it is always igual de... que and tan... como.

Why use Se me olvidó instead of just Olvidé?

Spanish often uses this "accidental se" structure for things like forgetting, dropping, or breaking something. It makes it sound like the event just happened to you, removing direct blame. While Olvidé is grammatically correct, Se me olvidó is much more common in everyday spoken Spanish.

Since "I" forgot, why is the verb olvidó (the "it" form) rather than olvidé (the "I" form)?

In the se me olvidó structure, the thing that slipped your mind is actually the grammatical subject, so the verb conjugates to match it. Here, the "thing" forgotten is the entire idea that you are fast. Since a concept or idea counts as a singular "it", the verb takes the third-person singular form olvidó.

Why does the sentence end with yo instead of mí?