How To disable Thinking using Gemini 2.5 Flash? thinkingBudget: 0 not working

Gemini API
,
1

Hi,

I read the doc
I add thinkingBudget: 0 like this but still not working! it’s slow as if Thinking is not disabled

when I tried OpenRouter version it’s faster , also when I tried Flash 2.0 it’s also faster than Flash 2.5 via Google AI Studio API with thinkingBudget: 0

did I do it wrong ?

  const requestBody = {
            contents: [{
                parts: [
                    { text: preamble },
                    { text: prompt }
                ]
            }],
            generationConfig: {
                temperature: 0.3,   
                response_mime_type: "application/json",
                thinkingConfig: { thinkingBudget: 0 }
                ,response_schema: {
                    type: "object",
                    properties: {
                        translations: {
                            type: "array",
                            items: { type: "string" }
                        }
                    },
                    required: ["array"]
                }
            }
        };
3

Hey @Basel , Seems there is a known issue with gemini-2.5-flash, which the engineering team is currently addressing. You can track the progress on this issue through the gitHub link here.

Thanks.