Hi there, by holding down alt while scrubbing thru the timeline you get a rough preview of what your effect will look like, if it looks ok hit enter to render the effect (this will be saved on disc until you make changes to the effect where-upon a re-render is called for). If you render your effects one at a time as you add them the process wont interrupt your workflow too much unless youve added lots of effects to a long clip.

Premier pro does render most effects in real time but requires a beefy machine and loads of ram and even then after a lot of effects have been added everything starts to sloooow doooooown so I still hit enter when I'm happy with the effect.

tonga