In 4.3, which performance features should I use if I already use W3 Total Cache

Enfold aside, W3TC on its own is not a recommended plugin. That said, I would strip everything back and start from the beginning.

1. Disable W3TC and clear all caches
2. Configure Enfold performance options as desired, testing all along the way for optimization (GTMetrix and/or webpagetest.org) and for elements not breaking

If performance is not where it needs to be after the above, use a plugin like WP Super Cache and do the testing process all over again. You may or may not need a caching plugin depending on many factors (Enfold performance, web hosting specs, etc.)

Here are a couple of articles that I’ve written or I’m in the middle of writing.
https://wpturnedup.com/optimize-wordpress-websites/
https://accuritpresence.com/enfold-theme-release-reviews-major-releases/

As a WordPress optimization shop, I’m in many communities around the topic and W3tC is no longer accepted as a solution. It can actually slow down a site. Just Google for yourself and you’ll find what you need to find as far as what others are experiencing. In general, it’s best to NOT implement caching until all other optimization is ironed out.

Great, continue to use it. You’re talking about 25% of the overall picture. Good luck.