Memory Leaks in FCPX
I Had these problems a lot with "memory leaks" in FCPX
For no apparent reason it started to use more an more memory
Then I discovered the following: If you have a AVCHD file on the highest level of an HD or SSD, FCPX sees the disk as a camera (card) and starts working on the whole disk as if it was a camera memory card, which fills up all the memory until it crashes. When you put the AVCHD file in a folder on the disc, this does not happen.
I had this issue for a long time, hope this helps others.
I have not experimented with other video container files like AVCHD, but pretty sure this is the same with them. It is not an Chrome issue, nor background rendering