Migration from 2.2.2 to 2.3.4 causes CPU overhead on servers


I migrated my application from rails 2.2.2 to 2.3.4 and from passenger
2.0.6 to 2.2.5.

Good news that my app now is eating less memory, and bad news that cpu
load is very high and rails processes are all have status RUNNING.

I didnt change any config options in my nginx and apache,
i installed passenger simply by command
/usr/local/ruby-enterprise-1.8.7-2009.10/bin/ruby /usr/local/ruby-

Did anyone have such problems with migration to new rails (effective
usage of memory but overhead of cpu)? Maybe it is problems with
garbage collector?

I am in panic, please help.

Thank you.