Various Blueprint actions Freeze Editor


  • Changing function inputs/outputs in blueprints freezes the editor for over a minute and continuously increases memory usage.
  • Compiling a blueprint takes longer and longer for each subsequent compile even if no changes were made. For example, one blueprint went from ~100ms compile to ~200ms, then ~400, then ~700ms, etc.
  • The freezing resets after deleting the Intermediate directory, however, this does not fix the above issues.
  • These issues seem to only affect blueprints of a certain type. Namely Actors, and Scene Components (possibly Actor Components, didn’t test). The issues are also shared between blueprints of the listed types. For example, compile times will increase across blueprints of the listed types. This hints at an issue with the parent classes.

Memory usage after changing a function input to array (blueprint editor window wouldn’t open):

Compile Time After no changes were made

Compiled immediately after. again no changes were made


I have attempted to reproduce this issue, but have not been able to do so.

  • Are you seeing this in a clean project?
  • Could you please provide your dxdiag?
  • Is this only occurring in the 4.12 Preview?


I am marking this topic as resolved for tracking purposes, as we have not heard from you in a few days. If this issue persists, feel free to respond to this thread. For any new issues, please create a new Answerhub topic.

Have a great day