Thanks for taking the time to post. I'm so sorry to hear your TiVo® box is slow for you. You've come to the right place for help.
I've managed to locate your account to run a test on your TiVo® box. It's showing any obvious faults with the signal, hard drive or tuners. Could you please answer the following questions:-
Is it only Netflix you're having an issue with?
Is it slow to respond to channel/volume changes?
Do you have the same issue with any another TV box?
Look forward to your response.