like leveraging the Sequence can definitely help with performance if used properly

I am a little concerned about mixing processors backends in case processors rely on generated sources, but I suppose if it compiles for us it should be fine

Re: performance difference beyond stub generation: I got 2 conjectures. 1. In KAPT, the delegation to javac still builds the full AST and I guess it resolves everything. Although resolution in Java is considerably faster than Kotlin, it still takes time. If a KSP processor only focus on a small part of a large code base, it can be faster. 2. kotlinc reads libraries mainly from metadata, which is much more concise than bytecode. We suspect that this implementation is faster than javac which reads bytecode. So it can be faster if a processor processes a lot of libraries. If you're using incremental processing, KSP tracks dependencies dynamically while KAPT assumes the worst case. This can be a big difference. Though that currently KSP doesn't track inter-module dependencies (and always reprocess all) while KAPT does. For inter-module changes, KAPT has an edge for now.