Suggestion: Profile a couple of the scripts that show the greatest difference, under 5.61 and 5.8. That should highlight were the differences are and may allow you to make specific changes to redress the balance.
If you post your findings here, then somebody may be able to suggest work-arounds for specific areas. I have noted a certain amount of slowdown between the 2 versions, but nothing like 50%. That really does sound like you have a specific problem that could probably be addressed.
Examine what is said, not who speaks.
"Efficiency is intelligent laziness." -David Dunham
"When I'm working on a problem, I never think about beauty. I think only how to solve the problem. But when I have finished, if the solution is not beautiful, I know it is wrong." -Richard Buckminster Fuller
