Magento store optimization Suggestions?

Question

I want suggestions regarding Magento store optimization : Are these two Extensions Useful which one between these two should be preferred to buy??

https://mirasvit.com/magento-2-extensions/full-page-cache-warmer.html
https://amasty.com/google-page-speed-optimizer-for-magento-2.html

What is you suggestion regarding optimization ??? We are using Varnish have configured it to our site , We are using Elastic Search ...

What other suggestions do you people give :: Shall we go on buying extensions or go for advance java script bundling using baler ??