IntelliJ IDEA 2025.3 marks the official deprecation of K1 mode in favor of the advanced K2 mode, which has been widely adopted by users due to its enhanced performance, stability, and feature set for Kotlin development. K2 mode addresses the limitations of its predecessor by offering a rebuilt analysis engine that improves scalability and speed, facilitated by the inclusion of the Kotlin Analysis API. The transition to K2 mode has yielded substantial performance improvements, such as a 39% increase in code analysis speed and a 34% boost in the "Find Usages" feature, while also enhancing stability with fewer support requests and exceptions. While K2 mode has nearly achieved feature parity with K1 mode, ongoing efforts are being made to address rare feature usage and optimize performance further. User feedback has played a crucial role in shaping K2 mode, and IntelliJ IDEA plans to continue building on these architectural advancements to enhance Kotlin tooling in future releases.