Hi Vishal,
For starters, if you don't have any reporting done on DSO's then you don't need to generate the SID's for both of them. SO go to change mode of DSO and uncheck the option of 'Generate SID on Activation'.
Next, check if you have any routines written in any transformation then you can look for options to optimize them.
Also when you are loading in Cube then are you dropping the Indexes and recreating them?
Thanks
Amit