umg slow on mobile device

As the title states when i launch my game to a device (Samsung galaxy s4) the umg seems to be lagging behind and not updating as quickly as it should. i have gone through the mobile development stuff in Mobile Game Development | Unreal Engine Documentation and it didnt seem to have any effect. ive tried using is volatile and nothing seems to change.

UMG renders stuff to texture in separate pass that is later used as an input texture in main pass.

According to [Smedis’ presentation][1] (slide 9) this situation causes whole FBO (to which UMG is rendered) to be copied to RAM and then reloaded.

It’s possible that you are rendering your UMG in large resolution. This will cause significant copying time. Check resolution of your UMG widgets and make them as small as possible on mobile:


Hello King Pete,

If Mikom’s suggestions did not help, I have a few questions for you that will help narrow down what issue it is that you are experiencing.

Quick questions:

  1. Can you reproduce this issue in a clean project?
  2. If so, could you provide a detailed set of steps to reproduce this issue on our end?
  3. Could you provide screen shots of any blueprints and/or widgets that may be involved with this issue?

Hello King Pete,

We have not heard back from you in a few days, so we are marking this post as Resolved for tracking purposes. If you are still experiencing the issue you reported, please respond to this message with additional information and we will offer further assistance.

Thank you.

I have the same issue in my project. About 40 child buttons on mobile GUI cussing significant FPS lose. 3 Buttons about 60 FPS 40 buttons 6 FPS. I hope that Unreal will create mobile button without hover detection.

Hello Xaser3D,

Could you answer the questions asked of King Pete? Could also include the exact device being used along with the current OS that is running on the device?

I tested:
Meizu M3 Mini, mali 860, YunOS 3.1.6/Flyme OS5.1.4.0Y
LG G2 andreno 420 Lollipop 5.0
Samsung SM-T211 KitKat 4.4.2
Meizu MX4 PowerVR H6200MP4
Lenovo Lemon K30-T KitKat 4.4.2
and other model…

I think that the buttons have a lot of mathematics and calculations. It is necessary to make mobile optimized button version. Things like button hover 100% based on the line trace or object intersection and just unnecessary on cell phones. Changing button style to add identical image not an option on mobile platform only on PC. I optimize my project code on old devices
on purpose to see in first place the performance issue and different bugs.

You could implement this by created a widget blueprint that has only an image and an OnClicked event. From there you could substitute this widget in for any buttons that you may need.

I’m unable to find on clicked event for image only for buttons.

One more question it is possible to detect swipe movement above scrollbox using bluprint?

I found a solution to detect swipe movement above scrollbox it’s so simple )))

What I said above was unintentionally misleading. What I meant to say was that you could use an OnMouseDown Binding for an image. After it is setup, you could have same functionality as an OnClicked event. I hope this helps.