Add caching

[RReverser]

In most cases, exported function returns same true value. However, every time we call it, it has to get this value somewhere from engine's depths.

So I decided to do some investigations on how could we optimize performance in V8. Here are the results:
http://jsperf.com/local-true-vs-engine-true

As you can see, we can improve performance by simply caching value of true in local variable, and performance is critical for such a frequently used function.

Thoughts? Should we use such optimization or are there even better solutions?

[mde]

Sounds like a pretty simple optimization, and a pretty obvious improvement. Could you put together a PR?

[Manishearth]

I'm pretty baffled by why this works. Could someone explain this further? Why is returning a constant boolean slower than returning a variable?

I'm not very clear on " it has to get this value somewhere from engine's depths."; both V8 and Spidermonkey have a separate JS value for true (JSTrue in SM)

[Manishearth]

This is actually much slower when caching is added to the mix

http://jsperf.com/local-true-vs-engine-true/2

[mde]

Thank you for doing some more research and benchmarking around this. Micro-optimizations like this can be very tricky. I agree this should be removed.