I detected a performance regression in ifort 14.0 when using allocatable arrays. Optimization is perfect when using fixed size arrays, optimization does not work properly when using autoparallelization and allocatable arrays. This did work with full performance with ifort 13.1.
When single threaded code is produced, there is a partial - but extremely significant - loss of performance when using allocatable arrays.
I attached two files, ifortregression.txt, showing compiler version, compiler parameters and execution times, and matmul.F, the source code of the test programm.