From
Passmark:
Intel Core i7 M 620 @ 2.67GHz
Passmark CPU Mark: 2871
Rank: 114
Intel Core2 Duo T9900 @ 3.06GHz
Passmark CPU Mark: 2328
Rank: 145
I like
tom's hardware mobile cpu charts to compare, as it has a more diverse set of real world tests. But it doesn't seem too up to date with the mobile processors.
According to
Ars Technica, their innovative graphics switch technology also turns on the discrete graphics when you run something like LR or FCpro. Therefore, I think you should also factor in the GPU difference if you're contemplating an upgrade.
to be honest, I didn't know LR or PS utilized the GPU much.