ffmpeg is quick if all your doing is trimming videos with no re-encoding.
It's command-line driven but you can find guis for it.

 

If you are purely trimming and no other encoding, filters or anything then you could do that with a muxer in many cases (most of the ones I use have such functionality but I can't be sure all you find will have it), no need for any editing software to mix things up for -- something like virtualdub will also happily split up avi files but then you have to make sure you have direct stream copy selected.
In any case speed should be as fast as your hard drive can handle.

Be aware that if you go searching for a "splitter" then that is a different type of program/concept, though annoyingly some programs that will split apart video do have split in the name.

 

side recomendation:
if you have a fast enough upload speed, and you plan to share that movie, you can upload to youtube and use their own editor...
it made the job when i was in a friends house wanted to quickly edit a movie without the trouble of install anything and then unninstall when i was done

 

If all you need is FFMpeg (see above comments), I recommend Hybrid as a GUI.

 

I used it for so long and it was so good!

But the problem is that it isn't shipped with windows anymore. And the portable versions sucks (Many errors, crash, etc.)!

So what I ended using AVS Video Editor.

But if anyone have a open-source suggestion i will be all ears

 

Both of those are pretty bad. Not even worth a mention. Sorry.

 

Care to elaborate some? Neither are timeline or clip based (the more popular options for all the big NLEs/non linear editors) but both support opening video files, trimming said video files, appending video files, extensive quality improvement and alteration filters ( http://www.infognition.com/VirtualDubFilters/ http://www.avidemux.org/admWiki/doku.php?id=using:video_filters ) and export to usable formats.
For a 50 take, multicamera highly edited music or comedy show it would be a nightmare but if you just need to trim you walking back to your mark, a tangent that went nowhere or you walking to the camera at the end, and intersperse something from another source or another filming session then it does fine. Given the OP specifically limited things to just trimming then they are more than suitable, some might argue even geared for it. Bonus is the GUI shots you linked for no apparent reason have the buttons you would press to select the segment right there in the shots.

 

Windows Movie Maker is very simple and easy to find. If all you want is to cut clips out or cut down videos without any other editing, that's the way to go. It's incredibly easy to use.

Otherwise I like Sony Vegas. Pretty easy to learn, does the job. Can pretty easily edit videos/add transitions/ add audio/ etc.

As usual ask your local pirate for Sony Vegas. Massively overpriced otherwise.

 

Even smaller with h.265 and vp9, only the more recent 4k tv's seem to support it though for youtube and netflix,
1080p tvs only seem to have h.263/4 and vp6/8.