Update bark doc (huggingface#25234)

* add mention to optimization in Bark docs

* add offload mention in docs

* Apply suggestions from code review

Co-authored-by: Sanchit Gandhi <[email protected]>

* Update bark docs.

* Update bark.md

---------

Co-authored-by: Sanchit Gandhi <[email protected]>

docs/source/en/model_doc/bark.md

@@ -26,8 +26,67 @@ Bark is made of 4 main models:
 
 It should be noted that each of the first three modules can support conditional speaker embeddings to condition the output sound according to specific predefined voice.
 
+### Optimizing Bark
 
-### Tips:
+Bark can be optimized with just a few extra lines of code, which **significantly reduces its memory footprint** and **accelerates inference**.
+
+#### Using half-precision
+
+You can speed up inference and reduce memory footprint by 50% simply by loading the model in half-precision.
+
+```python
+from transformers import BarkModel
+import torch
+
+device = "cuda" if torch.cuda.is_available() else "cpu"
+model = BarkModel.from_pretrained("suno/bark-small", torch_dtype=torch.float16).to(device)
+```
+
+#### Using 🤗 Better Transformer
+
+Better Transformer is an 🤗 Optimum feature that performs kernel fusion under the hood. You can gain 20% to 30% in speed with zero performance degradation. It only requires one line of code to export the model to 🤗 Better Transformer:
+
+```python
+model =  model.to_bettertransformer()
+```
+
+Note that 🤗 Optimum must be installed before using this feature. [Here's how to install it.](https://huggingface.co/docs/optimum/installation)
+
+#### Using CPU offload
+
+As mentioned above, Bark is made up of 4 sub-models, which are called up sequentially during audio generation. In other words, while one sub-model is in use, the other sub-models are idle.
+
+If you're using a CUDA device, a simple solution to benefit from an 80% reduction in memory footprint is to offload the GPU's submodels when they're idle. This operation is called CPU offloading. You can use it with one line of code.
+
+```python
+model.enable_cpu_offload()
+```
+
+Note that 🤗 Accelerate must be installed before using this feature. [Here's how to install it.](https://huggingface.co/docs/accelerate/basic_tutorials/install)
+
+#### Combining optimizaton techniques
+
+You can combine optimization techniques, and use CPU offload, half-precision and 🤗 Better Transformer all at once.
+
+```python
+from transformers import BarkModel
+import torch
+
+device = "cuda" if torch.cuda.is_available() else "cpu"
+
+# load in fp16
+model = BarkModel.from_pretrained("suno/bark-small", torch_dtype=torch.float16).to(device)
+
+# convert to bettertransformer
+model = BetterTransformer.transform(model, keep_original_model=False)
+
+# enable CPU offload
+model.enable_cpu_offload()
+```
+
+Find out more on inference optimization techniques [here](https://huggingface.co/docs/transformers/perf_infer_gpu_one).
+
+### Tips
 
 Suno offers a library of voice presets in a number of languages [here](https://suno-ai.notion.site/8b8e8749ed514b0cbf3f699013548683?v=bc67cff786b04b50b3ceb756fd05f68c).
 These presets are also uploaded in the hub [here](https://huggingface.co/suno/bark-small/tree/main/speaker_embeddings) or [here](https://huggingface.co/suno/bark/tree/main/speaker_embeddings).
@@ -103,6 +162,7 @@ The original code can be found [here](https://github.com/suno-ai/bark).
 
 [[autodoc]] BarkModel
     - generate
+    - enable_cpu_offload
 
 ## BarkSemanticModel