Python 3, 24 bytes

print(' '.join(input()))

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Should be compact and fast

Python 3, 15 bytes (Courtesy of @Makonede)

print(*input())

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Python 3, 24 bytes (~0.03s)

print(' '.join(input()))

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Should be compact and fast

PowerShell, 23 bytes

("$args"|% t*y)-join' '

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This dosen't deserve seperate answer