720p slowmo looks choppy?

When I slow down the 720p footage the result is very choppy and blurry, but if I slow down 480p footage the result is smooth at the same playback rate.

The numbers:
Footage from Nikon D3100: 1280x720x12 at 30fps
Footage from some camcorder: 640x480x32 at 30fps
Program: Sony Vegas Pro 10, playback rate 0.35, "interleave every frame" box checked at rendering

I don't understand why they produce such different results using the same frame rate, is it because my computer is too slow to effectively interleave at 720p?

Slo-mo will look different on every camera based on its resolution.a 480p camera at 30fps will look way smoother than 1080p at 30fps. The reason being that the camera has to take a bigger picture for each frame, causing it so slow down and appear choppy.either get a faster camera and do 1080p at 30fps or just use the 720p at 30fps

The other real possibility is your computer is too slow to handle all that data.

I know because I was using an XP computer with a 1.3gb processor and I had problems with full
1080 video. I've since moved to a 3.3 Intel processor and it made a real difference.

Also consider your graphics card. If it's too slow as well that can cause you problems.

Slo-mo will look different on every camera based on its resolution.a 480p camera at 30fps will look way smoother than 1080p at 30fps. The reason being that the camera has to take a bigger picture for each frame, causing it so slow down and appear choppy.