I am changing the footage speed in Premiere Pro 1 to create a slowed down effect. The problem is, every time I render it, it looks jerky and is not smooth. I am using speed/duration and changing the speed percentage (which effects the duration too). The un-rendered footage plays back perfectly on the timeline, it's just the slowed down parts are jerky when rendered.

Some parts are speeded up to 115% but these are ok once rendered.

Can someone help me overcome this problem?