Possible steps for optimisation:
1. Bypass parsing JS(if it enabled) by CakePHP custom Dispatcher
2. Replace Apache to Nginx or use it both(Nginx for static content, Apache for page generation)
3. Minify all JS and CSS on the fly.
4. Maybe DB and CakePHP Cache Engine tuning needed.
I have enough knowledge and experience to fulfill such projects related to VPS optimisation, CakePHP developing and Mysql tuning.
You can not pay for the work until it is finished or task will not be finished at all.
Thank you for your intrest to my proposal.