The new cipher suites are fast. As Adam Langley described, ChaCha20-Poly1305 is three times faster than AES-128-GCM on mobile devices. Spending less time on decryption means faster page rendering and better battery life. Although the cipher part of TLS may not be the biggest source of battery consumption (the handshake is more expensive (PDF)), spending fewer CPU cycles on encryption saves battery life, especially on large files.
Cutouts is an open source application. Code licensed under the MIT license. Copyright 2018 Siddharth Kannan