Urgent Web Application Bug Fixing and Performance Optimization

My production web application requires a quick but thorough round of bug fixing and performance tuning. I am currently experiencing issues on both the frontend and the backend, and I need an expert who can address each layer without disrupting the existing architecture. Current pain points include slow page load times, which appear to stem from heavy assets and sluggish database queries, as well as occasional UI glitches in the layout that affect the design and responsiveness problems on tablets and some mobile devices. Your mission will be to track down and resolve the offending code, tighten up any slow queries or inefficient API interactions, and ensure the interface looks and behaves correctly across modern browsers and major devices. Deliverables for this project include clean, well-commented fixes for the identified frontend and backend bugs, measurable improvement in load speed and database response time (with before-and-after metrics), a polished layout with fully responsive behavior, and a concise report summarizing the changes, tests performed, and recommended next steps. I would like to wrap this project up within the next day or two. Clear, timely communication is essential to get this app running smoothly again.