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Auto Router v1.97: usage benchmarks and better quality for lower cost

Tin Lo
Tin Lo
AI Engineer, LiteLLM

LiteLLM Autorouter V2: routing accuracy on complex scenarios, 5.6x more accurate by reading the last N turns of the conversation before picking a model



🚀 Help shape the Auto-Router

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Already testing it? Share your results in discussion #32168.

v1.97 makes three changes to the auto router.

  • The LLM classifier now receives a window of prior conversation turns, defaulting to three. This improves accuracy of follow-up classifications from 14% to 78%, costs at most $0.61 per 1,000 requests, and no additional latency.
  • A new Benchmarks view prices routed traffic against an all-frontier baseline and reports the difference, and those savings now also appear in the Cost Optimization totals.
  • Session affinity is now off by default, following our previous post showing this was leading to worse quality without cost improvements.
Two defaults changed

classifier_context_window_size now defaults to 3 (LLM classifier only), and session_affinity now defaults to false (all routers). Config files are not modified, but the new defaults apply to any key left unset, so a config that never mentioned session_affinity will reclassify every turn after upgrading. Configs that set either key explicitly are unaffected.

Benchmarking the LiteLLM Rust AI Gateway: Overhead, Memory, and Cost

Ishaan Jaffer
CTO, LiteLLM

Last Updated: July 2026

We are launching an early beta of the LiteLLM AI Gateway in Rust, and we built AIGatewayBench to measure it against Portkey, Bifrost, and the current LiteLLM Python proxy. Across all four, the LiteLLM Rust gateway has the lowest p99 added latency and the smallest memory footprint by a wide margin: roughly 7x lower overhead and 9x less memory than the next-closest gateway (Bifrost), the lowest cost footprint, and the fastest whole-session times for coding agents. It holds its own on raw sustained throughput and pulls decisively ahead on overhead, memory, and cost.

Migrating LiteLLM to Rust - Building the Fastest and Litest AI Gateway

Ishaan Jaffer
CTO, LiteLLM

Last Updated: June 2026

Over the past year, we have heard the same thing from our users and our community: they want the fastest, most lightweight AI gateway they can run. We have heard you. We are addressing it by moving LiteLLM to Rust, and committing to sub-1ms overhead with a sub-100MB memory binary you can deploy. By the end of this migration, you will get a pure Rust server that can serve 100% of your AI traffic, with every hot path operation, including auth and rate limiting, running in Rust.

Want to help us build it?

We are opening an early beta and want to work directly with teams who care about a fast, lightweight gateway. If that is you, sign up here and we will get you testing the Rust gateway in your own stack, with a direct line to our team.

The reason it matters: under real load, CPU and memory climb with concurrency, and pods get OOM-killed at the worst time. Today the LiteLLM Python proxy peaks around 359MB of memory under load, and that cost multiplies across every pod, region, and retry you run.

We are already seeing the payoff in benchmarks. The Rust gateway serves about 15x the throughput (453 to 6,782 requests per second) on about 11x less memory (359MB to 32MB), and cuts per-request overhead from about 7.5ms on the Python path to about 0.05ms, well under the 1ms we commit to.

What you get​

You deploy a single Rust binary. It uses about 65MB of memory, gateway overhead stays under 1ms, and nothing in your setup changes: same config.yaml, same database, same client API, same providers. You keep LiteLLM's coverage of 100+ LLM providers behind one OpenAI-compatible API, with /chat/completions, /messages, /responses, and every other LLM endpoint LiteLLM supports today, now as the fastest and most lightweight LLM gateway you can self-host.

This is not a v2 and not a rewrite. There is no new major version to migrate to and nothing for you to change. The runtime under the hot path gets faster and lighter while your config stays exactly where it is.

We ship this the careful way. Each route moves to Rust only after it passes our full parity and end-to-end test suite, and it runs in production before the next route starts. Stability is the priority, and we target zero regressions on every release.