Ootje,
All the downloadable files were the same. No watermark, no 3D, no wmv, etc.
So it's hard to tell how this program is performing when I can only see one file out of a supposed five you uploaded.

Robert Smith, if you just Preview, then the selected file will be Ppreviewed:
https://www.dropbox.com/s/z0pog6km5wwmmm7/FirstOne.png
Select an other one then the preview will be shown form that file:
https://www.dropbox.com/s/gnhuknzhfjz13yn/Watermark.png
And also possible the download all of them to your own PC(at your own risk; I believe there is nothing wrong with these files, but I do not know everything):
https://www.dropbox.com/s/9i23n34k2lstksp/3D.png

peter,

FWIW & in case it helps at all...

MP4 & AVI are both video file containers that can hold different kinds of video inside. The kind of input & output video compression, the encoder settings when originally encoded as well as output encoder settings, the video frame size, & number of frames [fps] will all effect the speed of conversion -- so will the CPU [& often GPU], the read & write speeds to the storage drive(s), and any other software processes running at the same time. While video file size matters to you [why else convert the video?], the length of the video may be a better measure if you're comparing video converters using your laptop, since that lets you better predict how long similar conversions will take. And then remember that the conversion speed you measure applies to your laptop, so while handy to compare brand X & Y converters on your laptop, they likely won't apply for example using your PC.

With CPU-only video encoding, using as close as possible to 100% CPU is generally considered a very good thing, but as the number of CPU cores increases it becomes harder & harder to achieve, & is actually a good measure of the encoding software. With GPU assisted encoding you want to look at that use percentage instead, as the CPU percent will drop considerably. The detailed view of Windows Task Mgr. tells you which processes are using how much RAM, but unless you're close to running out of available RAM, it usually isn't something to worry about -- the RAM is there to be used, & using it is faster than using the hard drive(s).

Audio sync is a more difficult topic, since lots of things can effect it, including the software you use. You might have lost audio sync because of the input &/or output formats you used, because of the converter, because your laptop couldn't keep up processing the video & audio streams etc. I'm guessing that you chose a MP4 to AVI conversion to test the software [AVI has limited practical uses nowadays], & if so, test the kinds of conversions that you really want/need, and only try to fix it if it's a problem with those. You can try different converters &/or output settings, or you may have to change your workflow if the problem is the type of input video you normally use -- AVC/H.264 video &/or AC3 audio can sometimes be particularly difficult.

peter,
658 GB? No way Jose.

Basheer, he must mean 6.58.

David J Wilson,
Even if that is correct, I do not want to touch this program with a 10 foot pole. For one thing, many older computers with 32 bit system will not handle a file bigger than 4 GB.

Basheer, oops 658MB

David J Wilson, OOPs 658 MB. But still over 4 times bigger after conversion and the picture is smaller!

Basheer, The first computer I ever used had 448 BYTES of RAM! But then - I'm older than God.