Unicorn-Kanchana (Raff 5 'Lenore')

[terry martyn]

Does  such creative interpretation extend to a conductor who plays around with the composer's tempi?

[Alan Howe]

a conductor who plays around with the composer's tempi

That's what conductors do, isn't it? Unless one has a metronome mark, the rest is interpretation. And even then some metronome marks simply make no sense in performance.

In the case of Raff 5/first movement the marking is crotchet=168, which is very quick. As far as I can tell, Järvi is the only conductor who gets close.

[terry martyn]

I have always been fond of Herrmann's langourous interpretation of the first movement. Lenore is wallowing in her feverish dream.

You know what they say about a machine that ain't broke.

[Alan Howe]

a machine that ain't broke

Well, from the point of view of the specified crotchet=168, Herrmann's machine is distinctly down on power (roughly 132, i.e. between 20% and 25% too slow).