Ollama local model becomes ~7x slower through OpenCode than direct Ollama API

Description

OpenCode is extremely slow when using a local Ollama Qwen3.8 27B model, even though Ollama itself is not under significant CPU load.

The important issue is not a percentage slowdown, but the additional ~4 minutes of wall-clock time added by OpenCode.

Measured comparison

Setup | Time -- | -- Qwen3.8 direct via Ollama API | ~38 sec Qwen3.8 via OpenCode | ~4 min 41 sec Qwen3.8 direct via Ollama API | ~36 sec Qwen3.8 via OpenCode | ~4 min 39 sec

So OpenCode adds approximately 4 minutes per request compared with calling the same Ollama model directly.

Additional observations

• The same Ollama model responds quickly when called directly through the Ollama OpenAI-compatible API.

• With OpenCode, the OpenCode process can reach approximately 35% CPU.

• During this time, Ollama is often at almost 0% CPU, suggesting that the delay is not caused by model inference itself.

• The problem therefore appears to be somewhere in OpenCode / its AI SDK integration / request processing rather than Ollama model performance.

• I am not looking for a different model. The goal is to make the existing Qwen3.8 27B + Ollama setup perform normally through OpenCode.

• I am also not looking for a workaround that fundamentally changes the setup. I would prefer a simple configuration or software fix.

• If OpenCode cannot use the local Ollama model without adding several minutes of latency, I will likely return to AIStudio.

Important terminal observation

The same OpenCode/Ollama setup behaves differently depending on how OpenCode is accessed:

• Through iTerm2/SSH, the behaviour is noticeably different from

• Through macOS Screen Sharing.

This may be relevant because the OpenCode process appears to consume significant CPU while Ollama is idle.

Direct Ollama test

Calling Ollama directly is fast:

time curl -s http://localhost:11434/v1/chat/completions \
  -H 'Content-Type: application/json' \
  -d '{
    "model": "qwen3.8:latest",
    "messages": [
      {"role": "user", "content": "Reply with exactly: READY"}
    ],
    "stream": false,
    "reasoning_effort": "none"
  }' | python3 -m json.tool

Result: approximately 0.8 seconds.

Without reasoning_effort: "none", the same request took several seconds and returned ~37–38 reasoning tokens. With reasoning_effort: "none", it returned only 2 completion tokens and completed in ~0.8 seconds.

Environment

• macOS

• Mac Studio M1

• OpenCode 1.18.25

• Ollama 0.32.14

• Model: qwen3.8:latest

• Qwen parameters: 27.3B

• Quantization: Q4_K_M

• Ollama reports the model running at 100% GPU

• Ollama context shown by ollama ps: 32768

• OLLAMA_MAX_LOADED_MODELS=2

OpenCode configuration

{
  "$schema": "https://opencode.ai/config.json",
  "model": "ollama/qwen3.8:latest",
  "small_model": "ollama/gemma4:26b",
  "formatter": true,
  "permission": {
    "external_directory": {
      "~/My Drive/Development/**": "allow"
    },
    "edit": {
      "~/My Drive/Development/AIStudio/**": "allow"
    }
  },
  "provider": {
    "ollama": {
      "npm": "@ai-sdk/openai-compatible",
      "name": "Ollama (local)",
      "options": {
        "baseURL": "http://localhost:11434/v1"
      },
      "models": {
        "qwen3.8:latest": {
          "name": "Qwen3.8 27B (local)",
          "tool_call": true,
          "reasoning": false,
          "attachment": true,
          "limit": {
            "context": 262144,
            "output": 65536
          }
        },
        "gemma4:26b": {
          "name": "Gemma 4 26B (local)",
          "tool_call": true,
          "reasoning": true
        },
        "gpt-oss:20b-cloud": {
          "name": "GPT-OSS 20B (cloud)",
          "tool_call": true,
          "reasoning": true
        }
      }
    }
  }
}

The key point is that the model is explicitly configured in OpenCode with:

"reasoning": false

yet the direct Ollama API test showed that omitting reasoning_effort: "none" causes Qwen3.8 to generate ~37–38 reasoning tokens and adds several seconds of latency.

I would like to know whether OpenCode 1.18.25 / the @ai-sdk/openai-compatible integration is correctly disabling reasoning for Ollama/Qwen3.8, and whether there is a known issue causing OpenCode itself to spend several minutes processing a request while Ollama is essentially idle.

Plugins

No response

OpenCode version

No response

Steps to reproduce

No response

Screenshot and/or share link

No response

Operating System

Apple M1 Ultra, 26.5.1 (25F80)

Terminal

iterm2 and screen both give same issue