Help with synthetic keys

[#1]

I have four facts tables with measures in it. However, I also have four key fields in each of those tables that I need but it creates synthetic keys and affects the performance. How can I fix this?

[#2]

Thanks Marco. I've been trying this method. What if one of the tables didn't have a field as the others? (i.e forecast table only had week, product and location but NO version)

Would you do the same method for that one as well?

[#3]

We are using the similar approach of creating a Link Table(Bridge table) for removing synthetic keys as stated by Marco Wedel .

You can use combination of Autonumber() to create keys from a table which helps us to uniquely identify records and then use Link Table to concatenate into a link table.

You have to decide, what are key factors to define a unique key of a table. If for forecast table "product" and "week" are sufficient to maintain uniformity then use them, other wise u have to include version as well.