You will likely get better performance out of using Cloudflare alone for both security and performance.
Cloudflare has the following performance advantages of Cloudfront:
- CDN WebP support in Polish
- Support for HPACK in their HTTP/2 implementation
- Ability to cache anonymous page views with WordPress
- Railgun
Additionally, Cloudflare has Flat rate pricing so no need to worry about bandwidth fluctuation, unlike with Amazon. In terms of network size, AWS in 16 cities where Cloudflare is in 101.