Editing video very choppy on my PC

[ShivP]

Hi all

I am editing some 4K 30fps video from an iPhone on my PC

Whatever software I use, Camtasia or inbuilt Win10 Video Editor the rendered video comes out very choppy almost like 10fps instead of 30fps
However on my brothers "ancient" i5 4670k machine it works perfectly

Do I have some dodgy codec installed or something?

Thanks

 

[Destination]

What package and codec are you editing it into?
What format?

 

[ShivP]

What package and codec are you editing it into?
What format?

Hi
Not really sure about the package/codec stuff. I have tried MP4 and AVI, I also bought the HEVC Codec from Microsoft store.

 

[ShivP]

What package and codec are you editing it into?
What format?

in Camtasia seems there is no option on MP4 to change anything other than a percentage "quality", NTSC/HDTV. On AVI there are these options

 

[ShivP]

I also tried 'VideoPad' (old version) and the edited video actually comes out fine in this. however I would prefer to use Camtasia Studio as I am a little more familiar with this