Bruno Walter & Vienna Philharmonic (1938): 18 min 12 sec
George Szell & Cleveland Orchestra (1969): 21 min 30 sec
Otto Klemperer & Vienna Philharmonic (1968): 24 min 11 sec
Of course, some may object to the charges of musical fraud against these three conductors by pointing out that two of them (Walter, Klemperer) were Mahler's friends and disciples, while the third (Szell) was already a young performing conductor and pianist in Vienna when Mahler was still alive. Alas, this feeble attempt to protect the reputation of the above maestros is laughably unconvincing. After all, when it comes to how long a movement of a Mahler symphony must last, who would you believe: some baton-waving Mahler's pals who probably didn't even have college degrees, or chief music critic for the New York Times who has a doctorate in music?
* Tommasini, A., "Mahler's Haunting Ruminations at the Abyss", New York Times, June 6, 2008, italics mine.