If possible, could you please provide the specific numbers.

I'm assuming you're talking about mobile CPUs.

The Core 2 Duo T9300 (I'm thinking this is the CPU you are talking about) 2.5 GHz perform around the same, maybe slightly slower than the Core i5 430M series. With the Core i5 500M series, it will outperform the Core 2 Duo T9300.