Blueprints shouldn’t have any additional impact on GC compared to C++, it’s all about how much churn you generate (spawning and destroying actors, components, and objects). I’m not sure what you mean by ue4editor cache, but you can do “obj gc” in the exec console to force a GC.
There several improvements to GC performance coming in 4.11 and 4.12, both baseline optimizations (to GC itself, and to increase the number of UObjects we strip during cooking for things like materials and particle systems) and the concept of gc clusters, where you can opt in and say ‘this island of objects should be treated as a single object cluster for the purposes of GC’ which can help a lot when you have a densely connected subgraph of object references that only has sparse external connections.
Cheers,