VideoStudio :: Preview Display Freezing While Playing

I have come across - the 1st time - a series of mpg video clips which, assembled into a project file on a 3rd party usb memory stick, irregularly freezes the preview image and sound while playing, usually in the 1st or 2nd clip in the file. Searching for a reason, I have played the file on two machines across both usb2 and usb3 connections, and using different versions of VS, and the freezing of the play occurs in all of them. At different places in successive events. The same thing happens with individual clips in VS, and individual clips in other video player software like media player and VLC.

I've no reason to believe that the software or even the files are causing this. At least, not yet. The only common element seemed to be the memory stick, so I copied the files from the 3rd party item to one I know is usb3, opened the project file and after re-linking, played it. Same thing happened in the 3rd clip. The results to date suggest that the player software (any of them) in doing the background data load from the memory stick at some point is taking too long, and thus the freeze. Which led me to review the file formats and size.

The freezing files are interesting - mpg format, but way bigger than I had expected for the duration involved. For example, one of the freezing ones is 1min18sec duration and 99,791Kb in size. Compared to a 51sec 22,224Kb file taken on a different camcorder. The duration versus size differences are substantial (for only a 27 sec duration difference the size difference is nearly 5 times), and one wonders why? Both of them loaded into VS show as MPEG-1 format on a right click properties display.

As far as I am aware, mpeg-1 is the same as avi format, and mpeg-2 and mpeg-4 are compressed and thus smaller versions of the same file length without loss of quality. Why mpg file should freeze during play in VS X6, X5, media player and VLC, on a desktop and a separate laptop machine?