[Due for payment 2025-12-04] Add a recommendation to use ccache in the Android setup instructions to speed up local builds

[mountiny]

Coming from here

Background

Local Android builds are required when working on native changes in HybridApp and NewDot. In these cases, remote builds cannot be used, because they do not apply ongoing local native modifications. This means developers rely on local builds during iteration, so local build performance directly affects development speed.

Problem

When developers frequently switch between branches, a clean rebuild is often required to avoid Gradle build errors. This forces recompilation of many files that have not changed, significantly increasing build time and slowing iteration.

Solution

Add a short recommendation to the README encouraging developers to install ccache to improve local Android build performance. This aligns with the official React Native documentation, which recommends using ccache for native builds. CMake will automatically use ccache when it is installed, so no project configuration changes are required.

Impact

With ccache installed, repeated native builds reuse previously compiled C/C++ outputs even after clean builds and branch switches. Because most of our native C/C++ sources change infrequently, their compiled outputs can be reused across builds, making ccache highly effective.

This reduces local build times by approximately 40 percent, shortening development feedback loops and improving productivity with minimal setup effort.

Issue Owner

Current Issue Owner: @JmillsExpensify

[melvin-bot]

Triggered auto assignment to @JmillsExpensify (Bug), see https://stackoverflow.com/c/expensify/questions/14418 for more details. Please add this bug to a GH project, as outlined in the SO.

[mateuuszzzzz]

I prepared a PR, but I believe we should wait for this PR to be merged and released first.

[mateuuszzzzz]

PR in Rock was merged, waiting for a release