performance issue after upgradation

Dear All,

I am facing one problem, we have upgraded the existing 4.6c version to ecc 6.0 version for one of the client. And from the basis side everything is completed. But while I tried to run the z-programs in the new version i.e ecc 6.0 version it is taking long time than usual in 4.6c version. On observing the coding , the coding contains innerjoins of 4 to 5 cluster tables. Is this could be one of the reason for longtime execution or else any other reason is there. Do we need to performance tune the programs or else is there any procedure to reduce the program execution time without optimising the code.

Please help me and thankful to you all in advance

Regards

Rayasam