LangSmith import optimization reduces initial import time overhead

Deferring specific langsmith imports in langchain-core reduces module import time, improving cold start performance for serverless and CLI workloads. Introduced in langchain-core 1.2.15.

Monitor application startup time metrics after upgrading to langchain-core 1.2.15. Expect reduced cold start latency in AWS Lambda, Google Cloud Functions, and other serverless environments where import time directly impacts request latency.