I'm a professional Magento developer from Viet Nam. I have been working with Magento for more than 5 years. I can work with Magento 1, Magento 2, linux servers, AWS, cache system .. I can optimize magento site and servers to get fastest speed (average loading time will be from 1 - 3 seconds)
I have read your project requirement, you are having redis, and varnish cache but the theme and source code might not allow full page cache working. I can investigate and help you fix this.
I will be more than happy to do this job for you and corporate long-term