Local LLM Takes 3 Minutes to Say Hello? Fixing Slow Ollama on an AMD RX 6800 XT (Vulkan to ROCm)
A local model taking two to three minutes to answer "introduce yourself in one sentence" is not normal, even on a mid-range GPU. On my AMD Radeon RX 6800 XT the cause turned out to be two stacked problems: the agent app was sending a ~20,000-token prompt with every message, and Ollama had silently fallen back from ROCm to Vulkan, where long prompts are processed very slowly. Fixing the second one took a 25,000-token prompt from about 9 minutes to about 30 seconds. Everything below was measured on one Windows 11 machine on 2026-09-28 with Ollama 0.34.4 and qwen3:8b / qwen3:14b (Q4_K_M). Your numbers will differ; the diagnostic steps will not. The symptom A desktop AI agent pointed at local Ollama showed "Worked for 2m 53s" for a one-line greeting. Cloud models in the same app answered in seconds, so the app itself looked fine. Short prompts typed directly into ollama run felt fast, which made the slowness look random. Before: a one-line greeting took 2 ...