The most important factor is memory speed and not CPU speed. Mememory speed is much slower than CPU. As Poser consumes and process a huge amount of memory, this amount doesn't fit in the CPU cache and always create a cache miss slowing all the process.

Several cores do help, but the problem continue to be memory access speed, all the cores share the same memory, so the bottle neck is memory. When a core is accessing memory the other 49 cores will need to wait doing nothing, if they need to access memory.

Newer processors and its respective mother board will run faster because they have faster memory bus speed, better management of memory and faster memory that use, but the chipsets of the motherborad have a great importance. Depending on the combination CPU, motherboard and memory you even can have case where a slower CPU rendering much faster that a newer and faster CPU.

A 64 bit rendering software will run much faster because it can use many GB of memory and load all into memory without using virtual memory that is very much slower than memory, but it also depend on how is written this software.

With Intel processors in 64 bit mode a 64 bit software runs faster than the same 32 bit software. With AMD processors it has no importance, 32 and 64 bit softwares run with the same speed.

Stupidity also evolves!