[Yusuf Lateef]"is it neccesary to render every clip in FCP ?"
Only if the footage you are importing isn't a format that FCP is designed to work with. FCP has a list of codecs it edits...that can be found in the EASY SETUP menu in the Final Cut Pro Menu. If your footage isn't listed, then you need to convert it to one of those formats. When you do that, then FCP will make sequence settings that match...and you will have no rendering.
[Yusuf Lateef]"if u wanna go fast then how to edit movies in FCP ?"
Convert footage to match. Or use another editing app that doesn't require you to convert the footage.