[Misc] Small perf improvements

[Yard1]

Small performance improvements in different components, discovered during profiling. Look at commit list for details!

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[github-actions]

👋 Hi! Thank you for contributing to the vLLM project.
Just a reminder: PRs would not trigger full CI run by default. Instead, it would only trigger fastcheck CI to run, which consists only a small and essential subset of tests to quickly catch errors with the flexibility to run extra individual tests on top (you can do this by unblocking test steps in the Buildkite run).

Full CI run is still required to merge this PR so once the PR is ready to go, please make sure to run it. If you need all test signals in between PR commits, you can trigger full CI as well.

To run full CI, you can do one of these:

• Comment /ready on the PR
• Add ready label to the PR
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🚀

[Yard1]

/ready

[comaniac]

LGTM

[cadedaniel]

Some test failure

[DarkLight1337]

It looks like you are calling list after chunk_list in each case. Wouldn't that defeat the point of making it a generator function?

Edit: Never mind, I see it being used in https://github.com/vllm-project/vllm/blob/main/vllm/core/block/block_table.py#L265

To make the code a bit cleaner (by reducing the number of list calls), I suggest adding a new generator function iter_chunk_list to be used in for loops (e.g. in the above case), while keeping the existing semantics of chunk_list.