`NewCarbon()` performance optimization

[Agility6]

Hey, I compared versions v2.6.2 and v2.5.0 and found that the NewCarbon() method in 2.6.2 might have performance issues.

1. v2.5.0 fetches Location via time.LoadLocation() — system call overhead
2. v2.6.2 fetches Location via ReadFile + Unmarshal — I/O + JSON processing introduces performance loss

Performance optimization for v2.6.2 could be achieved through caching.

I'll attempt a PR if feasible.

[kuafuRace]

Hey, I compared versions v2.6.2 and v2.5.0 and found that the NewCarbon() method in 2.6.2 might have performance issues.

1. v2.5.0 fetches Location via time.LoadLocation() — system call overhead
2. v2.6.2 fetches Location via ReadFile + Unmarshal — I/O + JSON processing introduces performance loss

Performance optimization for v2.6.2 could be achieved through caching.

I'll attempt a PR if feasible.

Welcome PR