Syntax highlighting is a CPU-intensive process which we run a lot while rendering posts and while using the composer preview. Moving it to a background worker releases the main thread to the browser, which makes the UX much smoother.
Co-authored-by: Mark VanLandingham <markvanlan@gmail.com>
Co-authored-by: Robin Ward <robin.ward@gmail.com>
Co-authored-by: Mark VanLandingham <markvanlan@gmail.com>