New install of Blender; extremely slow when panning a video I have read a lot of posts here and on other forums about Blender being painfully slow, to the extent it closes in on being unusable. Here is my scenario:

I have a 11 second 4K video (30 MB file) that I import into Blender &quot;Video editing&quot;
I drag the video onto the timeline/sequencer
When I drag the time-marker, it is super laggy, updating maybe once every second
When pressing SPACE to play the recoding, the framerate is around 5

Hardware:

AMD Ryzen 9 3900X 12C on base clock 3800 Mhz (on GIGABYTE X570 AORUS ELITE)
NVIDIA GeForce RTX 2070 SUPER, 1605 Mhz, 8 GB memory
32 GB DDR4 RAM
Samsung NVMe SSD (4x 8.0 GT/s)

Software:

Windows 10 x64
Blender 2.91.0 (latest, installed from Steam due to this post)
Blender is set to use &quot;CUDA&quot; under Preference --&gt; System; my graphics card is selected
Win, Blender and the video file are all placed on the same NVMe SSD drive
Nothing else is running except the basics; CPU and GPU is idle, plenty of RAM available, as well as space on drive

I suspected something weird with the video file itself, so I took a look at it in MediaInfo. This info doesn't tell me much:

Anyways, I thought that maybe the video file is bad somehow, so I imported it into Adobe Premiere (latest version), and the video works fine there, no lagging, smooth time-scrolling and playback.
Here is a video of the Blender lag: https://screencast-o-matic.com/watch/cYlO6c878q

Note that I am click-and-dragging the time-marker, so I am holding it all the time
Both drag and playback is extremely laggy as you can see
Note that it is not the Blender UI that is slow; it isnt, its snappy and fast

Here is a video of the same video file imported into Premiere: http://somup.com/cYlO6e27hY

As you can see, its smooth and fast

The above leads me to conclude that it is not the specs of the computer, the hardware, OS or the video file; this seems to be a Blender-specific issue.
Questions:

Is this lag in normal / expected behaviour in Blender?
I read some &quot;hacks&quot; around it, to use some lowe-resolution hacks, but I am not after hacks, I wanna know if this is normal, or if I am missing something?
Unfortunately, I believe this is 'normal'. It's 4k video, so it takes a lot to edit and needs a lot of optimization that is just not there yet.
Make sure you update your video drivers because if they are not up to date that might cause issues, but I think it will lag some in any case. I would not consider using lower resolution preview a hack since that is what is done in many video editing aplications in situations like this, it is a pretty standard thing to do. Video editing in Blender is being very actively improved at the moment so you can also try the experimental nightly builds, however be aware that they are in development and might be unstable so maybe save your work more often and save a backup file from the stable Blender version.