Using a proxy API with JavaScript can help reduce bandwidth usage and improve performance by bypassing speed limits imposed by websites. A five-step process involves getting an API key, subscribing to the Quick Proxy API, spot-checking proxies, using the proxy API with JavaScript, and optionally saving a list of proxies to a JSON file. To connect to the proxy API, one needs to install Node.js and use the Request implementation in JavaScript to test the proxy's IP address and port. The results are saved into a JSON file, and the process can be repeated to build a large list of proxies. However, using multiple proxies at once is not recommended due to potential issues with blocking, and managing many proxies requires checking for failures and keeping track of their status. Additionally, using a proxy does not guarantee anonymity or improved security, but it can help with privacy and identity protection if used responsibly.