Vue Guideline: Reactivity — Use shallowRef for large objects. Description: Avoid deep reactivity for performance. Do: shallowRef for large data structures. Don't: ref for large nested objects. Good Example: const bigData = shallowRef(largeObject). Bad Example: const bigData = ref(largeObject). Severity: Medium. Docs: https://vuejs.org/api/reactivity-advanced.html#shallowref.