Should I use Cloudflare's proxy DNS or does Firebase Hosting provide adequate security against Ddos, rate limiting, etc?

[NM]

Hi all, 

 I recently migrated my custom domain to Cloudflare and am managing the DNS records there. However, one feature of Cloudflare is the ability to proxy the DNS to help prevent Ddos attacks, etc. 

Questions:

1. Should I enable this proxy feature?

2. Does Firebase Hosting already provide some built-in protections? If so, is Cloudflare's Proxy feature unnecessary?

I want to ensure that I am making my site as performant as possible, and I wasn't sure whether enabling the Cloudflare proxy feature could cause the site to slow down. 

Thank you for any guidance or clarification on my questions.