Optimize App Performance & Security

I have a fully-functioning application that users like, but it has started to feel sluggish and I’m concerned about occasional crashes and potential security gaps. My goal is simple: tighten the code so... (Budget: ₹750 - ₹1250 INR, Jobs: Application Performance Monitoring, Continuous Integration, Security Auditing, Software Testing, Testing / QA, Usability Testing, Web Security)