Pipelines in 5.1.1, 5.2

Yesterday I actually found out that pipelines like workflow, look much heavier in the latest releases of Sitecore.
We run our custom workflow actions and discovert that, undependent of which action was taken, running trough a pipeline took lot more resources and time then before. As a matter of fact I’m trying to figure out what’s actually different as interfaces aren’t really changed between the latest releases and let’s say the 5.0.x branche.
When someone ahas the same experiences as I’ve, I’m definitelly interested. Then I can recreate it and do I really have a case for support.

The stuff above occurs in 5.1.1.9 and it’s equivalent in .Net 2.0: 5.2.0.3
Coming back to here as soon as I’ve got more information.