Speed up singleton decorator so it can be used more places

[bdraco]

Proposed change

Speed up singleton decorator so it can be used more places

This is roughly a 60% speed up to the singleton decorator. (normal functions only)

Type of change

• [ ] Dependency upgrade
• [ ] Bugfix (non-breaking change which fixes an issue)
• [ ] New integration (thank you!)
• [ ] New feature (which adds functionality to an existing integration)
• [ ] Deprecation (breaking change to happen in the future)
• [ ] Breaking change (fix/feature causing existing functionality to break)
• [x] Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request:

Checklist

• [x] The code change is tested and works locally.
• [ ] Local tests pass. Your PR cannot be merged unless tests pass
• [ ] There is no commented out code in this PR.
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• [ ] I have followed the perfect PR recommendations
• [ ] The code has been formatted using Ruff (ruff format homeassistant tests)
• [ ] Tests have been added to verify that the new code works.

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• [ ] Documentation added/updated for www.home-assistant.io

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[bdraco]

performance tested with

import timeit

from homeassistant.helpers import singleton

@singleton.singleton("X")
def x(hass):
    return {}


class H:

    def __init__(self):
        self.data = {}

print(timeit.timeit(stmt='x(hass)', setup="hass=H()", number=1000000, globals={"H":H,"x":x}))

[bdraco]

thanks