PERF: DataFrame.T

[jbrockmendel]

• closes #xxxx
• tests added / passed
• Ensure all linting tests pass, see here for how to run them
• whatsnew entry

Perf regression caused by #44593 (not yet released, so no whatsnew)

from asv_bench.benchmarks.reshape import *
cls = ReshapeExtensionDtype
dtype = cls.params[0]
self = cls()
self.setup(dtype)

%timeit self.df.T
91.1 ms ± 1.75 ms per loop (mean ± std. dev. of 7 runs, 10 loops each)  # <- master
163 µs ± 3.8 µs per loop (mean ± std. dev. of 7 runs, 10000 loops each)  # <- PR

[jreback]

thanks @jbrockmendel