[ruby-core:29017] [Feature #3010] slow require gems in ruby 1.9.1

Issue #3010 has been updated by Miao Jiang.


I trace 'active_record', I found Gem::LoadError has 3 difference performance.
version,time,percent
1.8.7 0.106,100%
1.9.2 orignal,0.184,174%
1.9.2 cut $: to $:[-9,9],0.158,149%

My ruby 1.8/1.9 compile step:
./configure optflags=-O3
make -j4
make install

New test code: 
# foo.rb
st=Time.now.to_f
#$:.replace($:[-9,9])
require 'rubygems'
Gem::LoadError
puts Time.now.to_f-st

Test Command:
cat foo.rb;gem environment;(for i in {1..10} ; do ruby foo.rb ; done)|awk '{print $1;s+=$1} END {print "avg:", s/NR}'

Test Result:
1.8.7 0.106 100%
1.9.2 0.184 174%
1.9.2cut 0.158 149%

Test Details:
http://gist.github.com/344366
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