I am having a very stupid problem with video editing software. I made a 7 minute video, I want to trim off the last 2 minutes of the video, finally I want to save the video in the exact same format as I opened it in.

Now please explain to me why every editing software, and tutorial I look at, end up resulting in a 3 hour video conversion process turning what was once a 400 mb file into a 7 GB file... This shouldn't take more than 1 minute and the file should get smaller.... I have tried like 5 different programs now, what the hell is wrong here...