Editor Timeline horribly slow - RAM preview?

Hello folks - Please forgive me if some of my terminology isn't 100% accurate as I just started using HFE 2017 last night.  I am using 4k mp4 clips and mp3 audi.  After cutting them all up and placing in the editor timeline, I try to playback the complete work.  However it is so choppy, pausing on frames or skipping them altogether-unusable. I only have about 6 minutes of 4k video and two songs.  This doesn't seem 'too much' to render.  My PC is 4Ghz i7 intel quad core processor.  16GB of ram (I set HFE to use 75%/12GB total).  And my video card is a Nvidia 750 GTX w/ 1gb of ram.  Any issues with this hardware that could be causing the slowness?  I thought there was a RAM preview mode where it will cache all the work on the timeline?  I can't find it in the program anywhere.

Thanks all!



  • @net1994 RAM preview is only available in composite shots, not on the main editor timeline (sadly).

    Regarding your machine specs, I'll have to let the Windows folks chime in on that.

    On a general performance note, though, I think you may be underestimating the processing power needed to edit 4K footage.  What a standalone media player does when playing back video is completely different than what editing software does, which requires frame-by-frame access.

    One thing I strongly suggest (if you haven't already done so) is to transcode your footage into something that's optimized for editing.  This video from @Triem23 dives into all the delicious details of how and why:


  • @net1994  Like you, I am not up on the ram preview settings, but a lot of times this kind of stuttering lagginess is just the software having problems in the preview window.  This will be especially more of an issue, I think with 4K footage, and this is compounded by the number of effects you having going on too.  You can set the level of preview up at the top right corner right next to the options tab to half and even one quarter and get some relief to allow you to do a quick view to look for timing issues and such. This won't affect how the project renders at all.  You can preview at a quarter and it still renders with Antialiasing, I believe.  Hope this helps you out someway.

  • I don't have any 'effects' going.  Just stringing along video clips and adding audio.  (Are those considered effects?)  I'm not adding any particle effects, etc, etc.

  • @net1994

    I have similar spec machine to yourself (i7-3770k, GTX 760 and 16mb RAM) using Hitfilm Pro4 . I don't use 4K video but have stacked many videos, songs etc without a problem..

    I do sometimes see slowdown in quite complicated composite shots but
    If all your activity is in the editor then I would guess it's not your machine spec.

    Silly question... if you do something similar with non-4k footage do you see the same issue?

  • @net1994  I wouldn't consider adding audio as effects.  I was speaking more of particle effects and such, but really I suspect the 4K footage causes a slow down on preview especially if set to FULL or ANTIALIASED, but I am certainly no expert here just what I have experienced through trial and error.

  • To start HitFilm's performance with h.264 isn't the best and virtually all cameras produce MP4 files that have a very high decode overhead meaning they hammer a CPU during playback and editing. Beyond that, working with 4k video is pretty harsh under the best of circumstances and you need a pretty stout machine. @NormanPCN did some testing and put together demo videos to show what could be expected with a system similar to yours.

    Hitfilm timeline 4k performance demo video

    Tl;DR HitFilm 2017's native Cineform support (Mac users should use ProRes) gives you the best performance but you'll end up with much larger files which could cause you hard drive throughput problems. NormanPCN's own NormanAVC is also a decent performing choice that doesn't give you the huge files Cineform will. Both options are covered in the video @jsbarrett linked to. 

    For general reference a quad core CPU like yours is generally considered the absolute minimum for 4k work with 8 or more high frequency cores being recommended. Intel jumps to recommending a workstation with dual 12 core Xeon CPU's for "serious" 4k work.

  • @net1994 "16GB of ram (I set HFE to use 75%/12GB total)"

    That is a terribly high amount of memory setup for RAM preview. That setting is not about amount of RAM Hitfilm will use but for ram preview only. Hitfilm has no limits on the ram it will use for general use.

    "And my video card is a Nvidia 750 GTX w/ 1gb of ram.  "

    Is the 1GB RAM listed correct or a typo. That is a tiny amount of ram for the GPU, especially for 4k work.

    In general 4k work is really a big step up in work for an editor relative to 1080. In terms of pixels being processed, 4X more. A computer that is smooth at 1080 needs a lot of power in reserve to step up and still be smooth at 4k.


  • net1994 

    Alternatively, if you have a lot of storage, why not proxy your footage? It should help.

  • @NormanPCN

    Do you think if I upgraded my video card from 1GB of VRAM to 4GB, would that make a difference in editor mode?  Otherwise I have enough RAM and my CPU is definitely able to handle the load.  When I encoded my first 6 minute 4k footage, it only took about 20 minutes.  This seems good to me.

  • @net1994 Video cards cannot have their memory upgraded. At least none that I have seen.

  • @NormanPCN - I meant buying a new video card that already has 4GB of ram.

  • edited August 2017

    @net1994 I'm not really comfortable answering that unless I could do some tests. I don't know of a way to limit my GPU to 1GB ram.

    Speaking generally, GL can access textures from main memory so short GPU ram can work but in that circumstance it would get a slowdown relative to if all textures fit into GPU memory.

    FxHome does recommend 2GB of ram for 4k/UHD work. If one does not do particle sims or 3D models or composite layers can you get away with less than recommended. I would want to test before commenting (sticking my foot in my mouth).

    Also recommended does not mean always good. It is always possible to have too many textures and shuttling to/from main memory will occur. It is just how complicated a project/composite have you setup.

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