System 1: 2007 noteoobk: Toshiba U205-S5067: Core 2 Duo T7200, 4GB RAM, 320 GB HD
System 2: 2011 notebook: Toshiba R830-10P: Core i7 2620M, 8GB RAM, 256 GB SSD
This benchmark result is not only affected by the processor. Almost all system components affects the result. The processor is only the main component.
Evaluating overall performance, for compiling Linux Kernel and generate its RPM packages for Fedora 15: Core i7 system is 2.85 times faster than Core 2 Duo system.
I've run the steps described on: http://kdpeter.blogspot.com/2011/05/steps-to-test-kernel-build-on-fedora-15.html, for the kernel package kernel-184.108.40.206-27.fc15.src.rpm.
The only difference to the procedure described above is that I added the command "time" in the building step, to be able to compare necessary time to do same task.
$ time rpmbuild -bb --with baseonly --without debuginfo --target=`uname -m` kernel.spec
System 1: Core 2 Duo
System 2: Core i7
See more benchmarks: http://blog.parahard.com/search?q=benchmark