Selenium is the slowest of most web scraping libraries, but compared to others (Scrapy, Requests etc.) it's the only one that can scrape from dynamic websites. A dynamic website is one which the html is constructed at run time, and must be loaded for any information to be present. Other scraping libraries don't load the website, they just use the URL to retrieve the data associated with it within the web, which is why they run faster. However, with scraping from instagram, a dynamic website, there are no faster alternatives to selenium.