I do, but it's also easy to sound smart when you're standing on the shoulders of very smart people. @jdalton and @petkaantonov are two that I've regularly followed and read their code for learning purposes. IRHydra by @mraleph is a great tool for learning about V8 internals and examining what's going on under the hood. Bluebird is an amazing example to follow if you
really want to optimize, however the vast majority of libraries and apps don't need to concern themselves with some of the crazier optimizations that are performed there.
The biggest takeaways that I've had are mainly that if you really want to optimize, then write the kind of code that the various engines can optimize best. With that in mind, TypeScript is not only a great language, it's actually a great performance tool since it can help you to identify polymorphic functions that maybe could be changed to monomorphic ones if they're in the hot path.
I've got another fun hacky kind of optimization for you though that I've mainly used for benefit in some angular code/expressions that are executed potentially millions of times. If you can make some assumptions about the name of the property being accessed for security reasons and it's going to be repeatedly used, compare the following:
// Setup
const makeGetter = (prop) => new Function("obj", "return obj." + prop");
const slowGetter = (obj, prop) => obj[prop];
const fastGetter = makeGetter("foo");
const obj = { foo: "bar" };
// Test
slowGetter(obj, 'foo');
fastGetter(obj);
This is primarily an optimization for Internet Explorer, but if I recall it was somewhat positive in other browsers at the time as well. It makes more sense if you consider it in the context of executing a simple angular expression repeatedly, though 1.6.0 might narrow that gap significantly now that the expressions sandbox was removed as I think they generate code similar to my "makeGetter" factory. Haven't re-tested yet.