I have made movies in older versions on laptop, but have struck problem with 2012 version Windows 8.1

I can get there and have successfully made a movie and published; but it was extremely tedious and time consuming. At the project stage, when inserting clips, the whole project would stop for minutes at a time. Then when playing back at project stage, the play-back stops frequently for minutes at a time. It took forever to finish. The program then made the move okay in good time.

I have made a very short movie (a couple of clips) without an issue (with clips from smart phone0; and at another time with a few clip with the same stopping problem (with GoPro clips). Could that be a relevant factor?

I know i have a below specs computer, but not sure just where it's failing. I'd like to know so that when I go and purchase a desktop, I need to get it right.

I'm using a brand new beaut Sony Vaio Pro 11: 4th gen Intel Core i7-4500U dual core processor 1.80Ghz with turbo boost up to 3.00Ghz. I'm asuming that the processor capacity and speed should be fine. Would that be true?

The graphics is certainly below spec: Intel HD Graphics 4400 .

However, I've been very pleased with the computer's performance in playing GoPro clips (despite being below their specs re graphics) so i thought it should handle Movie Maker.

Main Question is would the hesitating and stopping at project stage be the program itself (divorced from the specs of the computer); the processor; or the graphics; or a combo?