We're not restoring cache on all builds.

yarn

Here's the time it takes to install npm modules in android by restoring cache:

Because we don't do it on ios builds, here's the difference:

Restore cache: https://github.com/RocketChat/Rocket.Chat.ReactNative/blob/develop/.circleci/config.yml#L18
Save cache: https://github.com/RocketChat/Rocket.Chat.ReactNative/blob/develop/.circleci/config.yml#L41

fastlane

Something similar should be done on fastlane by following Fastlane's best practices: https://docs.fastlane.tools/best-practices/continuous-integration/circle-ci/