<1kb light and claims to be “significantly faster than most other deep comparison libraries”, but current benchmarks (better ones coming soon) only cover one small and one very large object, so YMMV on the speed. Also full TypeScript support, if that’s your bag.

import diff from "microdiff";

const obj1 = {
	originalProperty: true,
};
const obj2 = {
	originalProperty: true,
	newProperty: "new",
};

console.log(diff(obj1, obj2));
// [{type: "CREATE", path: ["newProperty"], value: "new"}]