I dug a bit deeper and it seems that with transformers==4.37.0 everything works fine with other HF hosted models (like Llama) but you'll rightfully get this when trying to use Gemma:

ImportError: cannot import name 'GemmaForCausalLM' from 'transformers'

After installing transformers==4.38.0 the fine-tunning speed of Llama drops to 25% (?!?) of what used to be for a reason that I think HF should fix. Testing Gemma it seems I'm hitting a hardware limit as Gemma has a hidden size which is bigger than the available CUDA cores. This seems to make both inference & fine-tunning about 25 times slower than similarly sized Llama 7B. I guess some operations have to be broken down in multiple round trips to the GPU due to my low CUDA core count.

All in all, even if HF fixes the recently introduced slowdown, Gemma seems to be fine-tuneable in reasonable amount of time only by the lucky ones with access to A100/H100.

EDIT: I managed to hack my env to be able to run inference on Gemma with transformers==4.37.0 by keeping the necessary classes in loaded in RAM. It works about 4x faster but still very slow. And both the 7B and the 2B versions behave the same way.

EDIT2: I tried latest transformers from main branch (4.39.0.dev) and behaves the same as 4.38.0.