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An Evaluation Study of Generative AI Systems: Framework-Aware Performance Under Real-World Constraints

Abed Matinpour, Farhoud Jafari Kaleibar, Sara Fehresti, Shaylin Ziaei, Marin Litoiu

International Conference on Performance Engineering, 2026

Abstract

The widespread adoption of Large Language Models (LLMs) in enterprise applications has created a critical need for systematic evaluation of Generative AI Systems (GenAIS) that integrate orchestration frameworks, foundation models, and deployment optimizations. This paper presents the first comprehensive evaluation study specifically designed to evaluate the performance trade-offs between orchestration frameworks (LangChain, LlamaIndex), foundation models, and deployment constraints across multiple application domains. Our study systematically evaluates eight foundation models across question-answering with Retrieval-Augmented Generation (RAG) and mathematical reasoning tasks, measuring latency, accuracy, resource utilization, and power consumption under various optimization strategies including adaptive context windowing and concurrent request processing. Through extensive empirical analysis, we demonstrate that framework selection significantly impacts system performance independent of model choice, with task-specific trade-offs emerging across workload types. For retrieval-heavy RAG workloads, LlamaIndex delivers 3-15% lower latency, around 60% lower peak memory usage, and 2-4% more energy consumption. For reasoning-intensive mathematical tasks, Langchain achieves higher accuracy across all tested models and provides more predictable latency profiles and reasonable resource consumption, making it preferable for strict SLA environments. Adaptive context windowing does not…

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