Firefox has consistently been much quicker to approve updates. They also allow source code to be submitted to, in order to better verify the extensions behaviour and possibly do diffs on extension versions.
The process for extension approval is still very human-driven, so there's a few things to help speed up the process:
- Understandable abstractions: eg separate view code from logic, so it's easier to understand the application
- Try not to transpile or obfuscate, as it becomes extremely difficult to determine behaviours and capabilities of the app
- Simplify as much as possible, as someone else has read through and sign-off saying its a "safe" app. The simpler the quicker it can be understood...