bin2dec run time performance on different Matlab versions, same PC

A simulation I do runs very slowly using R2009a (64-bit) on my PC (Win 7; 64-bit; i7-2600; 16GB RAM). If I run the same program with R2013a (64-bit) on the same machine the total simulation time is >4 times faster. I've traced the main problem using the profiler to the built in function bin2dec. In the former case it uses 401sec vs 14.6sec in the latter, or x27 slower in R2009a vs R2013a.

What is the reason bin2dec would run in different ways in the two versions?

[Siddharth Sundar]

I am just taking a stab at this here. The upgrade in speed of execution of certain functions that are called within the bin2dec function should be the cause of this. Profiling the R2009a code and comparing it with the profiled version in R2013a should give you an idea of which individual functions within bin2dec are faster in R2013a (Specifically look at the code inside of the bin2dec function)