Abysmal Rails and Ruby 1.8.6_p287 performance on x86_64 Linux

Hi,

I’m wondering if it’s a known problem but recently I had to revert a
production server from 1.8.6_p287 to 1.8.6_p114 because the performance
was abysmal. ./script/runner took nearly 40s to load the Rails
environment before doing anything useful on a Core2Duo 2.66GHz running
Gentoo Linux 64bit.
./script/console was affected too (~40s to prompt) and our most used
controller actions were 2 to 4 times slower.

Is it a known problem of p287 ? If the problem exists for x86 it is at
least smaller (./script/console is slow to initialize, but takes only
around 5s on weak laptops) than on x86_64.

Lionel