Both models
i7-2640M and
i5-2500 are based on
Sandy Bridge architecture.
"Sandy Bridge codename was originally ""Gesher"". The development began in 2005 and four years later, the first Sandy Bridge CPU was presented. The most prominent features are Intel Turbo Boost 2.0, AES encryption and SHA-1 hashing acceleration, Advanced Vector Extensions (AVX) 256-bit instruction set and the ability to have up to 8 physical cores or 16 logical cores through Hyper-Threading."
Using the multithread performance as a reference, the i7-2640M gets a score of
54.9 k points while the i5-2500 gets
86.9 k points.
Summarizing, the
i5-2500 is
1.6 times faster than the
i7-2640M. To get a proper comparison between both models, take a look to the data shown below.