Rendering is required when the source material is in a format that is not compatible with FCE, - or - when the source material is being edited to a timeline that is a different format than the source material.
In FCE, click on one of your source clips in the FCE browser and, once selected, type Command + 9 to see the item properties for the clip. Either report those properties or take a screen shot of the item properties pane and post that here.
Now click on the icon for the Sequence you are editing in the FCE Browser, and again, once selected, type Command + 9 to see what the properties are for the sequence your are editing and either report those properties or take a screen shot of the properties pane and post that here.
Yes - your question had much to do with the issue.
I was dealing with very different file formats and even file size.
I found that m4v is very slow for FCE to process.
I also found that I can convert files to FCE format much faster in a side program - I used Squared 5 Streamclip to cut the videos down to the clip I required, then saved them as Apple DV/DVCPRO-NTSC with the sound at AAC 48 128. It processed much faster in Streamclip! Then imported without the need to render at upload! I was very pleased to say the least. The output file is .mov and it seems like this makes your FCE much happier!
We have too many options and not knowing what the options actually mean allows it to work, but really slowly!
My biggest concern is - why was it sooooooo hard to find information online about this. I searched forever before posting a question. The hardest thing is trying to word the question to be short and find the words that will key into the answer since the words you use is how search works. Search doesn't read vibe - only keywords and frequency creating GOOGLE rank so it will show in the search.
Thanks for the direction. I had read a lot of things but this was the direction that got me back in control of my MAC.