First things first
I am using Final Cut Pro X version 10.0.8 when working with video, which you get through the App store on your mac. I love the software because you can work in real time and not wait for rendering. That works in the background.
No matter what video editing software you use I highly recommend maxing out the RAM on your computer. I have 16 gigs of RAM on my Macbook Pro 15″. If I had a desktop I would have even more RAM.
You need a fair amount of free space on your hard drive as well. This is why I recommend running the projects off an external drive. The program is on the main drive, but the clips and video are on my external drive.
I recommend 20% or more free space on your main drive. As you fill up the external, its performance will also slow and this is why my next recommendation will improve your experience with Final Cut Pro X.
Second
By default Final Cut Pro X will show you all Events and Projects on all mounted storage devices. You are in essence loading all your projects on all your drives every time you open Final Cut Pro X.
Event Manager X gives you control over your Events and Projects so you can manage what you want to be visible in Final Cut Pro X’s Event Library and Project Library. So, you could have multiple external drives with various projects on them and Event Manager lets you decide what is visible.
Instead of launching Final Cut you launch Event Manager X. As you can see in the screen capture above those with a check are what will show up. Just uncheck and it doesn’t show up in Final Cut Pro.
What the program is doing in the background is moving your “Events” and “Projects” from their normal folders into “Hidden” folders. See the example above.
Now lets say you have a few projects in the works. You finish one and send it for approval to the client. While you wait on their feedback and changes you can then close Final Cut Pro open Event Manager and uncheck that project and event for now. Then just check the event and project you want to work on next. As long as you have that “Re-open Final Cut Pro X” at the bottom, when you click on the button to move the events and projects it will launch Final Cut after it moves everything and then you only see what you are working on in Final Cut Pro.
The reason for using Event Manager X is not to make things look neat in Final Cut Pro X, it is to improve the performance of Final Cut Pro X.