Movies not playing smoothly when created in Microsoft video editor

Hi,

I have some videos I shot on my new iphone, and they all play fine on my phone. I wanted to combine them all into a movie. I downloaded them onto my brand new Lenovo laptop, purchased Aug 2020 ( I have updated all the relevant software since purchase), when I play the videos from my phone on the laptop they all play fine, no matter how I play them, in Windows Photos or on VLC player etc.. but once I combined them all into a short 2 minute movie on Windows Photos/Video the playback is all jerky and slow???