[1] Learn more about multithreading and how it works:

Multithreading in Python - Official Python documentation on the threading module.
Concurrency and Parallelism in Python - A comprehensive guide on concurrency and parallelism in Python.
Understanding Python GIL (Global Interpreter Lock) - Learn about the Global Interpreter Lock and its impact on multithreading in Python.
Introduction to Multithreading in Python - A beginner-friendly tutorial on multithreading in Python.
Python Multithreading Tutorial - An in-depth tutorial covering the basics of multithreading in Python.

[2] Learn more about sorting algorithms, their time complexity, and efficiency:

Sorting Algorithms - GeeksforGeeks provides detailed explanations and visualizations of various sorting algorithms, including Merge Sort and Bubble Sort.
Big-O Notation - A beginner's guide to Big-O notation, which is commonly used to describe the efficiency of algorithms in terms of their time complexity.
Interactive Sorting Algorithm Visualizer - Visualize how different sorting algorithms work and understand their performance characteristics using this interactive tool.
Comparison of Sorting Algorithms - Toptal provides a comprehensive comparison of various sorting algorithms, discussing their strengths and weaknesses.