GitHub Copilot Cuts Inference Costs Through Four Efficiency Changes

GitHub disclosed four engineering changes to GitHub Copilot that reduce model-inference costs without degrading task quality¹. Removing line-number prefixes from the view tool cut per-user daily inference cost by about 3% in online experiments. Selective output compression, shortened task-tool prompts, and batched completion notifications contributed additional savings, with prompt compression alone removing roughly 1,300 tokens per turn for a 2.9% drop in normalized cost per active hour. Separately, migrating Copilot code review to shared file tools reduced review cost by approximately 20%. All changes were validated through offline benchmarks and controlled A/B experiments before shipping.