Huge corpus, few hits, not used recently

I have been using SpamSieve for 10+ years. I set it up and have ignored it because it worked so well!
Recently I was looking at the corvus and noticed that I have hundreds of words that have only one or two hits and they have not been used in years. Is there any benefit to cleaning out these old unused words?
And how about words that I see with about equal good and bad hits? I don’t really understand how the system works, so I don’t know if those are doing any good either.

Yes, it could reduce SpamSieve’s RAM usage and make it slightly faster.

I would leave those as-is, unless they haven’t been used in years.