‘Despite feedback’. Was that feedback clearly given in a sit down? With more than 4eyes present? Confirmed afterwards in writing to the employee, in a clearly worded ‘here is what we discussed’ email, stating behavior and output has to be stepped up? If ever it came to a discussion be it personally or even legally, do you have a track record to prove to yourself you did enough to warn him? If yes, then let him go. If it’s ambiguous, I would reconsider, from a legal and personal pov. Depending on the amount of vesting after this cliff, it might be worth it to let him go w some of the shares two months from now, and take your loss (moment of learning) for not resolving this in a more timely manner, and be more on top of it with other employees.