You will have problems no matter what you go with. Don’t think just because you switch all your problems will go away. I work on both FCP and PPro and FCP has more problems!! So much has to do with hardware configurations. Once you have those problems worked out you will have a better editing experience.
Sounds like nested sequences to me. Do you have any? If you are working on an original sequence that has been nested you are going to bring the system down to a hult. The trick is to turn the little eyeball off on the video track for the nested sequence. This way premiere is not trying to display the results in both places. This way you can edit the original sequnces as fast as it was from the beginning.
Did you install the CC plug ins with After Effects? If not go back to your disk and install them. They have a simple wire removal plug in. It works really well!!
Do you have After Effects? If so, you can use the remove grain filter. Works very well but it is a render hog. To get an idea on how to use it there is a tutorial on the disk that came with 6.5.