perf: optimize code performance

[kirklin]

Changes

• Optimize the code performance by using more efficient functions.

Details

• Use splice method in remove function to remove an element from an array instead of creating a new one.
• Use slice method in exclude function to make a shallow copy of the original array instead of modifying it directly.
• Use which.sync method in cmdExists function to check if a command exists instead of creating a child process and executing a command.

Reason for Change

The original code had some performance issues due to the use of inefficient functions. By optimizing the code, we can improve its performance and make it more efficient.