Multiple sampling rates in Simulink - to speed up simulation

Hi,

I have a system developed in Simulink where simulation of 60 seconds took around two hours to complete, at the end I would need to run the simulation for 3 hours (as it involves battery where battery's parameters would need longer time to see noticeable change for example the change in state of charge etc), so it means more than 300 hours might be needed to run this simulation which sounds so bad.

That comes the idea to implement multiple sampling rates in my system.

I have done some readings to find out that there are few options to do so:

1. Rate transition block

2. set the specified sample time at the "Function block parameter" of each block

I would like to know what is the difference between the two?

If I want to use method 2, do I still have to use Rate transition block?

It appears to be quite messy in using either of the above methods, is there a more elegant way to implement multiple sampling rates in a single Simulink file?

Appreciate any inputs, thanks!!!