As a video editor my self...
Beach balls will always be there with video.
The thing is that the video software has to pull an stream of data continually and that causes problems with the buffers.
When you load a software, those are small packages of data with no timing.
One thing you can do is to check what sort of codec you are using when editing.
For example H264 is a codec for delivery, not for editing because is compressed into packages. Many times video cameras uses that sort of codec to save space.
For video editing you need something like Apple Pro Res HQ, it separates the packages into individual frames. That was the video editing software do not need to decompress on the fly when you are editing.
Those may be the reason of your beach ball, specially if you use HD.