binary packages versus source

[pietia <pietia.moo@gmail.com>]

hello ,

i wonder why some of packages compiled from source are faster than 
precompiled debs.

for example - why the ruby interpreter in all tested version (look here 
,please   http://www.ruby-forum.com/topic/125344 ) 1.8.5,1.8.6, 1.9 is 
much more faster

when is compiled from source ? because of optimization for universal 
architecture in debs ?