Rewrite website framework to it is fast

My website is built on cakephp and is very slow with a very large mysql database. I would like you to rebuild the website backend and optimize it so it is fast and that the backend framework is not so complex. It is significantly slowing down periodically thoughout the day at various times. It has a large mysql database. Once this is complete, you will duplicate the rebuild on 3 other websites with same backend but different frontend. Measurement of success (how you will get paid). 1) Functionality of all 4 websites must be the same with no bugs / errors. 2) Make average response time measured over 14 day period via site24/7 from california as less than 500ms, 3) No response times may be greater than 800ms via site24/7 from california during the 14 day period measured on any particular point in time during the 14 day in #2 above. 3) You complete this project within 7 days of promised completion date, and I have 8 days to verify functionality, then validate 14 day response period. I must validate measurement of success with 1 website first before you receive the access to the other 3 websites. Promised completion date must be when all 4 websites are complete. Payment: if measurement of success is complete for all 4 websites, then I will pay you 100% via escrow. No payment will be made until then.