I'm not a native speaker so to understand the difference between past simple and present perfect is giving me a headache sometimes. I have learned, that when it is used in a sentence a time adverb describing a past event, I need to use present simple. But a few days ago I heard on the TV the following sentence:
It is better than what you have done previously.
But I would use:
It is better than what you did previously.
previously, yesterday, last week - all of these adverbs are set the story into the past. At least to me. Please, correct me if I'm wrong.