batched_mm is slow on cpu
Author: IlyasMoutawwakil
Pull request: yes

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Fixes # (issue)
<img width="1099" height="152" alt="cpu" src="https://github.com/user-attachments/assets/d6d96856-382e-46a0-be76-e900e3997179" />


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Comments:
The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_43438). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

thanks @stevhliu I updated the table and left one note about the decode-stage optimization on gpu.

@vasqu I switched to bf16 on cpu+grouped_mm+compile, imo it's better to test the grouped_mm on cpu here because it's what a user will get by default, switching to batched_mm will pass the tests but won't catch errors in the default cpu path. wdyt ?

View the CircleCI Test Summary for this PR:

https://huggingface.co/spaces/transformers-community/circle-ci-viz?pr=43438&sha=1d01c7