In my opinion, the I-140 processing times for EB2 and EB3 cases are almost identical.
Earlier (Before three, four months), it used to be like EB2 is processed atlease one or two months ahead of EB3.
I still see that trend for Concurrent applications, but for CP option cases, I do not see a good trend indication at all.
So, It is safe to assume that EB2 & EB3 I-140 petitions at NSC are processed with in + or - one month from each other.