Vadym Kazulkin presented on adopting Java for serverless applications on AWS. Some key challenges with Java include large cold start durations due to initializing the JVM and dependencies. AWS Lambda pricing is based on requests and compute duration, so cold starts increase costs. Techniques to reduce cold starts include using the AWS SDK 2.0, pre-initializing dependencies, and minimizing artifact size. Tooling like Lambda Power Tuning and AWS Lambda Powertools for Java can help optimize performance and reduce costs for serverless Java applications on AWS.