Ruby is very slow

I have a PC with 2 processors of 2GHz and 4go of ram. I use RVM with ruby-1.9.3-p194-perf and rails 3.2.3. When I load my rails application, it take a few time and I think it's not normal.

This is some example :

time rails new speed_test
 ...
 real    0m7.240s
 user    0m4.484s
 sys     0m0.184s
 
 time rails g scaffold Articles title:string description:text
 ...
 real    0m4.910s
 user    0m4.052s
 sys     0m0.348s
 
 time rake db:migrate
 ...
 real    0m4.172s
 user    0m3.716s
 sys     0m0.244s
 
 time rake
 ...
 real    0m15.981s
 user    0m14.045s
 sys     0m1.048s
 

This is some short commands but, with some hundred of tests, it's very long, even with spork.

Do you have a solution?

Thanks a lot!

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