Stuttering in Mobile Preview and FPS Cap

Development Platform & Builds Mobile
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1. I’ve come across a strange occurrence, where the Mobile Preview stutters badly, even though it claims it’s running at 60 fps and there’s nothing taxing at all about the scene. The Play in New Editor Window preview, however, runs smoothly (for the most part) with only occasional stutters (for some unknown reason). I’m running a 6-core i7-5930K @ 3.5 GHZ, with 32 GB RAM and a GTX 970 with 4 GB RAM. I am not using any SSD, only HDD, 1 TB 7200 RPM WD Black (OS), 2 x 4 TB 7200 RPM WD Red Pro (storage, separate drives, non-RAID).

I’ve uploaded a video of this issue, (if you watch the platforms going by it’s easy to see the stutter) and you can also reproduce it easily in 4.14.1 by opening a new SideScroller (3D) template and launching a mobile preview. If you look at the text, “Side Scroller Template” on the wall while moving side-to-side, you will see a twitching at regular intervals.

2. Additionally, I am wondering why the mobile preview (PIE) is only showing ~60 fps while the New Editor Window preview is showing ~120 fps. Is there a fps cap set for the mobile preview? If so, how does one disable it?

Thank you for your time in looking into this issue.

~Adam Janz

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I should mention I’m using the latest NVIDIA driver 376.33.

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Problem solved: it seems the stuttering Mobile Preview can be easily fixed by EITHER of the following:

  1. Enable Vertical Sync. Using the ~ key, enter the following console command: r.vsync 1
  2. Raise the max FPS. Using the ~ key, enter the following console command: t.maxfps 120

EDIT: Also, if you want to keep either setting active at all times during a Mobile (PIE) session, a simple way to do this is adding an Execute Console Command node to your Event Begin Play and typing one of the solutions listed above into the “Command” field. You can also use the command stat fps in another Execute Console Command node to view your current fps at all times if you wish.

~Adam