After updating resque-scheduler it started to behave really weird. The CPU would stay almost all the time around 100%. I don’t have a fix for that, but for now downgrading should be enough. You need to downgrade to following versions of those gems:

gem 'resque', '1.25.0'
gem 'resque-scheduler', '2.0.1'
gem 'rufus-scheduler', '2.0.24'