Garbage Collection causing lag 4.9

since update to 4.9 Garbage Collection is causing serous lag pausing the game for a split second and often causes characters to fall through the floor.
This is for all my projects that I’ve converted to 4.9 this even happens when there is no garbage to collect, initially the lag was every minute, if i set Garbage Collection to 3 seconds in the project settings the game lags every 3 seconds.

Garbage Collection was not an issue in my games in 4.8 and previous, Please Advise

UE4 Ver 4.9 and now 4.9.1 build from launcher
Mac OSX Yosemite 10.10.4

Hi ,

I have not been able to reproduce this here. Can you provide a screenshot of your Garbage Collection preferences (or just list all of them?) Also, what are your Mac’s hardware specs? Lastly, would you be willing to send your project as a zip file to me in a Private Message on our ?

Please provide as much of the requested data as possible and we will continue to investigate this issu.


Hi , Attached PC spec and Garbage settings, the time is set to 5 sec for testing. ill Zip up a project ASAP.

Hi ,

I’m testing on a Mac (Late 2013) Same specs running: OSX Yosemite 10.10.4, I do experience the lag when set for 3 seconds but not when set for 5 or 10 seconds. Do you find this to be the case?

Also, I did not experience the character falling through the floor (Played about 20 rounds). I also tried with Parallel GC off. Again I was not seeing any lag after 5 or 10 seconds.

Let me know if increasing to 5 or more seconds helps with the lag.


the lag is the same no matter what the collection time (3 5 30 or 1min)

the lag is reduced to a slight stutter with Parallel GC set to off and again no matter what the time is set at

here is a vid set at 5 sec with Parallel GC on


Hi ,

Thanks for the response and posted video of what you are experiencing. I have used this in addition to your project to enter the following bug report: JIRA [UE-21252]. When this issue has been addressed we will notify you with an update to this post.

Thank you for the feedback

This ticket has been closed out. While you will not experience notable GC performance when playing in editor, improvements have been made in GC performance for the packaged build.