Google is once again tweaking its search algorithm with a new change that should have some benefits for users. The company announced in a Thursday blog post that it will rank mobile-optimized sites higher in search results starting April 21. Sites that work well on a smartphone will get a “significant” boost over other sites, the company says. The change should ensure that people conducting Google searches on their phone typically arrive on easily-readable sites rather than messy desktop-based layouts that are hard to navigate on a small screen.