I built a legal-case management platform on CodeIgniter 3 and MySQL that imports very large Excel files, relies on ChatGPT for document drafting, and handles payments through PayPal plus a couple of other gateways. Usage has grown fast and the cracks are beginning to show, so I’m looking for someone who can go through the full stack and tune it for speed, stability, and clean integrations. Here is where I need you to focus: • Database queries – several reports now take minutes to run. You’ll profile slow SELECTs, redesign indexes or even the schema if necessary, and make sure batch Excel imports no longer lock tables or exhaust memory. • Code performance – refactor controller / model logic, tighten loops, add caching where it makes sense, and clean up any legacy CI3 patterns that are dragging response times. • Third-party integrations – PayPal, ChatGPT, and a secondary payment gateway must run smoothly. For PayPal in particular I want noticeably faster processing, stronger error handling, and rock-solid security around webhooks and IPN callbacks. Typical tools in play: MySQL 5.7, CodeIgniter 3.1.x, PHP 7.4, AWS EC2, Git. If you have experience running CI3 on newer PHP versions without breaking legacy helpers, even better. Deliverables I expect: 1. Optimised SQL scripts / migration files and a brief report on changes made. 2. Refactored CI controllers/models with comments highlighting performance fixes. 3. Updated PayPal integration module that passes speed, error-handling and security tests. 4. A short hand-off document so I can maintain your improvements after the job closes. Please include a quick note on a similar optimisation project you’ve completed so I know where you’ll start. Looking forward to shaving seconds—if not minutes—off every critical workflow together.