It might mean having to make choices. Choose what you think is most important. Write down key words and phrases and revise your notes immediately after class. Exchange notes with your classmates. Pool these notes and all involved will have a more complete set of notes.
Exchange notes regularly if it proves beneficial.
Leave large empty spaces for filling in information you missed. Use symbols that will help you remember what is missing. See the instructor after class. Take your notes with you and show the instructor what you missed. Suggest that he or she slow down.