Zoom recording edited with pinnacle studio

Hello together,

I edited a zoom recording with pinnacle studio. It was a long meeting with more than 3 hours and the original zoom recording file was about 1,5 GB. After editing the size became about 12 GB. Same format 1280 x 720 framerate 25, mpeg4 codec, everything the same as the original recording.

Has anyone an idea how this could happen? 

Greetings,

Karin