Hm...couldn't really tell. Seemed the same.
It's easy to forget that x86-64 doesn't just increase the memory address space, but also doubles the amount of general purpose and SIMD registers. This can lead to significant performance increases in CPU limited scenarios.
Perhaps they disabled the cloth physics in 32 bit due to the lack of additional registers for computation, which would result in an unacceptable performance hit. Cloth physics has always been very difficult to run on CPUs afterall..