Shotcut slows down and blocs everything

Windows 10, 62 b, 8 Go ram

the last version, 21.03021, 64 bits

Since the previous version, shotcut bug: during editing, for 1 to 2 minutes, everything is normal then it slows down, the images are jerky and everything hangs …
If we manage to finish the edit, which is almost impossible, shotcut cannot fully play a 3/4 minute edit …
Before, everything worked perfectly, editing and reading were very fluid.
I don’t think the problem is with Shotcut, but where?
Thanks for your help

Hello @andrelan , I am in my hometown and I have an 2 years old 8gb ram Macbook Pro with me currently, I noticed whenever I open 4 or 5 apps with shotcut then shotcut starts lagging and slowing down, So try to close all others apps while working on shotcut, Then you will have very less lag.

Do you use “Preview Scaling”, if not see here:

This is exactly what is happening to me and only since the previous update.
Probably a problem related to windows

Editing activities are working fine (cutting, adding titles, key frames, etc.) but shotcut cannot read the timeline for more than 1 minute. It hangs (except the sound), sometimes it takes a long time to find normal playback for a short time. When it is blocked, the computer is blocked! It is a memory problem that I did not have before as if there was not enough memory. however I have 8 GB of Ram.

There is a similar post (with a possible solution) hereL

Thank you for your interest in my problem with Shotcut which I really appreciate.
I recall my system: recent Lenovo PC, Windows 10 family 64 bits, 8 GB Ram, Intel UHD graphics 620 card
Latest shotcut version: 03.21.21
Prior to the February update, Shotcut was performing very well.
Shotcut blocks the timeline from playing after 2-4 minutes. Sometimes the sound continues, the video starts again in jerks and then freezes. All commands are blocked.
I made a recording with OBS (this is an OBS tutorial which usually wasn’t a problem):
[journal appli.pdf (81.8 KB) ](
The scrolling of the timeline is first jerky (from 30 sec) then freezes (from 2 min). If, at this moment, I want to work on the editing, everything freezes.
When I want to close shotcut (2.15min), it takes at least 1 minute for it to respond …
It is difficult to describe more. I am attaching an application log but before shotcut hangs.
The other software on my PC is working fine.
Thank you for your help.

In the video I noticed that You had firefox opened Annotation 2021-05-01 140916 , if you have opened too much tabs (or even one) then it may be taking up large amount of ram, because browsers are memory hogger, here is an example:-


So, try to close all apps while using shotcut.


I agree with this.

8GB is the bare minimum for HD video:

Also, if the hard drive is busy being used for other things, then that also affects Shotcut. Make sure there isn’t any antivirus scans happening while you try to use Shotcut.

  • Restart the computer
  • Do not open any applications other than Shotcut
  • Try to edit

I tried shotcut, closing all apps: it still freezes.
Before, I could use it without problem with other open apps (, word…).
A message displayed when it froze “You are running low on availiable memory., please close some programs”.
I opened the task manager: shotcut, alone, at one point, uses 5.6 GB of memory or 96% (the number turns red!). no other major memory usage (maxi 90 Mo) … I’m not a specialist but I don’t understand, the RAM is almost 8 GB. There is still room!
I did a windows memory diagnostic. It’s OK.

Before what? Before you installed a newer version of Shotcut? Or before something else?

If the previous version of Shotcut works well on your system, you can keep using that. Sometimes people think that a Shotcut update has broken something so they go to an older version only to find that it doesn’t work any better. Eventually they find out that something else has changed on their system. Or that they started using more challenging source files and did not realize it. Or maybe the video mode has been changed to a higher resolution.

If you are unable to determine what changed for you, there are many techniques available to improve the performance:

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Just my perception, but the minimum specifications is just a general guideline for Shotcut to work. One thing you didn’t state is the specifications of the video you’re trying to work with.

Are you trying to process 4k video?
Are you working with variable frame rate video?
Do you have just 1 drive (a HDD - Hard disk drive), or SDD, or NVME?
Trying to edit from a thumb/USB drive?
Are the files in a cloud server?

There are just so many other variables from your computer just having 8gb of memory.

This 5.6 GB is what it uses directly. Any app which accesses files also uses more memory indirectly, in the form of file buffers, which are counted as part of the “system memory usage”.

I was experiencing the same sort of problems with 8 GB; all these problems vanished when I upgraded to 20 GB of RAM.

Excuse me but I am not a computer specialist …
the problems I described appeared with the previous version (in January or February).
I installed an older version and even the portable version: the problem persists.
Windows and applications are on an SSD (40 GB out of 120)

These are often small videos made with a digital camera, smartphone or with OBS, etc., stored on the computer. The assembly is short, maximum 30 minutes …

I’m afraid there is not enough memory, but how do I add ram on a laptop?
Thank you for your advice and suggestions.

Exactly which model laptop do you have?

Better is to get to your nearby computer store, As if you yourself change the ram of a laptop you could even damage your laptop, laptop are portable but not good for changing hardware ourselves, if you had a desktop then it was easy because desktop have enough large space to keep everything separately, but laptop are much smaller and packed tightly, Go to your nearby computer store, mostly they will not take more then 15$ for changing the ram, but the amount of buying more ram could get up to70-90$ for 16gb ram and 160-200$ for 32gb ram. And check what type of ram your laptop supports like DDR3 or DDR4, also get a higher speed for your ram, if you pc supports DDR3 then get 1600MHz, if your pc supports DDR4 then get 3000MHz or 2933MHz or the speed you laptop supports.

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it’s a lenovo ideapad 340

So as per web results you should go with this type of ram:- The Lenovo Ideapad S340 Laptop takes the DDR4 PC4-19200 2400MHz Non-ECC SODIMM memory type.

and upgrading to 16 gigs would be ok if you are working on 4k videos, In total you would need to spend less then 70-90$ according to amazon and some extra 15-20$ for changing the ram on a store, Almost maximum 110$.

Annotation 2021-05-02 125308

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It seems that 360p preview scaling is effective.
I did not know this setting and was using the default setting!
Shotcut played my test video on the timeline without slowing down or freezing. And there is some memory left.
Hope this is the right solution.
thank you all.

Was to enable…

…except that @Ar_D has been busy while I slept and arrived first. :grinning: :+1:

This is good advice.

I upgraded my own desktop from 8 GB to 20 GB, it has made a great improvement in Shotcut performance.
(The upgrade was difficult for me, due to tight spaces, and I am a computer engineer with decades of experience.)
Get an expert to upgrade your RAM.