Have you compared using the current config() method, with a version of it that uses Factory::get('config') to see the difference?

I find the helper method config() much more readable and pleasant and what I'd prefer to ask users to use if it makes sense. I'm assuming it speeds it up quite a bit since the big boost is the callStatic method in Factory, right? And as it stands, assuming the config file is used say 1000 times in a page load for an app, we're only looking at 0.000143 second increase with the proposed changes. While I think any performance boost is good, if the a modified config() call is close to the same speed I would prefer to stay with that.

I am agree with @lonnieezell, we already introduces config() to get variable config using feature Factories release

Indeed, the performance improvement in the Welcome page benchmark in this PR was very small. The numbers are so varied that it is hard to tell if there is any real improvement.

However, the performance of Factories should have improved as seen in the profiles.

It might be certainly better to use config(), although there is the overhead of a function call.
That way, the config() implementation can be replaced by another container or something.

However, DI containers, service locators, whatever, they cannot make the framework faster. They can only slow it down. So even if we improve that, it seems impossible to keep up with CI3.