Guides, articles, and production pain points from the team building fast-langraph — the Rust performance layer for LangGraph.https://fast-langraph.neullabs.com/en-ushttps://fast-langraph.neullabs.com/guides/caching-llm-calls/https://fast-langraph.neullabs.com/guides/caching-llm-calls/LangGraph graphs re-issue the same LLM prompts constantly. The fast-langraph @cached decorator drops onto your LLM call sites and eliminates redundant API spend.Fri, 10 Apr 2026 00:00:00 GMTguidecachingllmcost-optimizationhttps://fast-langraph.neullabs.com/guides/profiling-bottlenecks/https://fast-langraph.neullabs.com/guides/profiling-bottlenecks/Before you adopt fast-langraph or any other optimization, measure. The GraphProfiler adds ~1.6 μs of overhead per operation and tells you exactly where your wall clock goes.Fri, 10 Apr 2026 00:00:00 GMTguideprofilingdiagnosticsperformancehttps://fast-langraph.neullabs.com/guides/quickstart/https://fast-langraph.neullabs.com/guides/quickstart/Install fast-langraph, flip the shim on, and measure your first speedup. No code changes to your existing LangGraph application.Fri, 10 Apr 2026 00:00:00 GMTguidequickstartshiminstallhttps://fast-langraph.neullabs.com/guides/rust-sqlite-checkpointer/https://fast-langraph.neullabs.com/guides/rust-sqlite-checkpointer/Replace LangGraph's built-in SQLite checkpointer with the Rust-backed drop-in. Same API, 5–6x faster per operation, and up to 737x faster on the serialization step for large state.Fri, 10 Apr 2026 00:00:00 GMTguidecheckpointsqlitepersistencehttps://fast-langraph.neullabs.com/guides/automatic-shim-mode/https://fast-langraph.neullabs.com/guides/automatic-shim-mode/fast_langgraph.shim.patch_langgraph() monkey-patches LangGraph at import time, swapping in faster executors and Rust-backed channel updates. No code changes anywhere else.Thu, 09 Apr 2026 00:00:00 GMTguideshimautomaticexecutorhttps://fast-langraph.neullabs.com/guides/manual-acceleration-mode/https://fast-langraph.neullabs.com/guides/manual-acceleration-mode/When the shim isn't enough, explicit Rust components deliver the headline speedups: 737x on checkpoint serialization, 46x on sustained state updates, and 10x on LLM caching.Thu, 09 Apr 2026 00:00:00 GMTguidemanualadvancedoptimizationhttps://fast-langraph.neullabs.com/guides/migrating-from-vanilla-langgraph/https://fast-langraph.neullabs.com/guides/migrating-from-vanilla-langgraph/A step-by-step migration checklist: profile, adopt the shim, swap the checkpointer, add caching, validate. Each step is reversible and measured.Thu, 09 Apr 2026 00:00:00 GMTguidemigrationchecklistadoptionhttps://fast-langraph.neullabs.com/articles/why-python-deepcopy-kills-langgraph/https://fast-langraph.neullabs.com/articles/why-python-deepcopy-kills-langgraph/The 737x speedup on checkpoint serialization isn't magic. It's the direct consequence of what Python's deepcopy actually does — and doesn't do — to your agent state.Wed, 08 Apr 2026 00:00:00 GMTarticleperformancedeepcopyserializationcheckpointperformancehttps://fast-langraph.neullabs.com/articles/scaling-langgraph-in-production/https://fast-langraph.neullabs.com/articles/scaling-langgraph-in-production/Production LangGraph workloads hit three predictable bottlenecks: checkpointing, executor churn, and LLM redundancy. An architect-level look at the cost math at each stage.Tue, 07 Apr 2026 00:00:00 GMTarticlearchitectureproductionscalingarchitecturecosthttps://fast-langraph.neullabs.com/articles/executor-churn-the-58-percent-problem/https://fast-langraph.neullabs.com/articles/executor-churn-the-58-percent-problem/Most LangGraph invocation overhead isn't in your nodes or your channels. It's in ThreadPoolExecutor construction on every single call — 58% of wall clock on short graphs.Mon, 06 Apr 2026 00:00:00 GMTarticleperformanceexecutorthread-poolinvocation-overheadhttps://fast-langraph.neullabs.com/articles/langgraph-vs-fast-langraph-benchmarks/https://fast-langraph.neullabs.com/articles/langgraph-vs-fast-langraph-benchmarks/An apples-to-apples comparison across checkpoint serialization, state updates, end-to-end graph execution, and LLM caching — every number reproducible from the public benchmark scripts.Sun, 05 Apr 2026 00:00:00 GMTarticlecomparisonbenchmarkscomparisonperformancehttps://fast-langraph.neullabs.com/articles/when-not-to-use-fast-langraph/https://fast-langraph.neullabs.com/articles/when-not-to-use-fast-langraph/An honest guide to when fast-langraph won't help — small graphs, simple state, LLM-bound workloads. Optimization isn't free, and the wrong tool at the wrong time is just noise.Sat, 04 Apr 2026 00:00:00 GMTarticleopinionhonestyanti-patternwhen-not-tohttps://fast-langraph.neullabs.com/langgraph-issues/checkpoint-serialization-overhead/https://fast-langraph.neullabs.com/langgraph-issues/checkpoint-serialization-overhead/Production teams running LangGraph with non-trivial agent state hit a wall where every super-step pays 100+ ms in Python deepcopy overhead. This is the single largest source of p95 latency growth.Fri, 03 Apr 2026 00:00:00 GMTpain-pointhighcheckpointdeepcopyperformancelanggraph-issuehttps://fast-langraph.neullabs.com/langgraph-issues/large-state-memory-blowup/https://fast-langraph.neullabs.com/langgraph-issues/large-state-memory-blowup/Long-running LangGraph workloads see peak memory grow well beyond the logical state size. The culprit isn't a leak — it's deepcopy allocating parallel object graphs on every checkpoint.Thu, 02 Apr 2026 00:00:00 GMTpain-pointhighmemorycheckpointdeepcopylanggraph-issuehttps://fast-langraph.neullabs.com/langgraph-issues/redundant-llm-calls-in-graph-loops/https://fast-langraph.neullabs.com/langgraph-issues/redundant-llm-calls-in-graph-loops/LangGraph graphs with retries, branches, or reflection passes frequently send the same prompt to the LLM multiple times per invocation — inflating both latency and API spend.Wed, 01 Apr 2026 00:00:00 GMTpain-pointmediumllmcachingcostlanggraph-issue