You wrote a lot but said very little. Long render times can have all sorts of causes as can your layers disappearing. The latter probably simply comes down that you need to extend the layer or delete some keyframe you may have accidentally put in there. Either way, you have to provide more info or screenshots. No point talking about an invisible elephant in the room.
as for the problem after the render, here is a screenshot. this is the beginning of the video and its there. All those are 3D layers and they stay shown there before their time. The problem is the layers dont dissappear they stay showing on the screen before the time its supposed to appear. It only appeared when I rendered it.
The render settings I will just lower the graphic so its okay.
Sorry my first time on the forums. My bad and apologies
If you haven't adjusted your layers in and out points, they will be visible at 90 degrees rotation because they're not pointing directly at the camera.
Szalam's right about trimming layer in & out points, and here's something else: don't be afraid to make those layers' beginning rotatations something OTHER than 90-degrees from full-forward. Make those layers look as close to a thin, narrow line as you can. Then, when you trim the in points to the spot where the animated rotation begins, it'll look just they've appeared out of nowhere. The same thing applies to rotating them out of the picture... just in reverse order.
As for slow renders, let me guess: you're on a laptop. If you have less than 8 gigs of memory, turn off the multiprocessing: it isn't doing you a bit of good. Turn off any kind of hardware acceleration, too: it's just as useless. And DO NOT render to h.264. Render to something lossless, like quicktimes in PNG or Animation codecs... or a lossless AVI if you want. Then use Adobe Media Encoder to make the h.264.