Glitchy and chopped video after export

Hi!

I've just finished editing a 2,4 min video. After exporting it's slow and glitchy in some parts.

Used the desktop version. Checked the MAC system requirements – everything seems to be alright.

Is there a way to fix this problem? I still have two more free exports.

But I was thinking to upgrade in order to use it for my work.

Thanks a lot!