I have been using Hitfilm in the past, but it has always been too slow for me to be usable. Most of the time I would use DaVinci Resolve instead, because it is much faster. My current project needed some FX though and I have a new computer, so I installed Hitfilm Express 2017. The workflow is great and though it is still quiet slow, I was able to accomplish what I set out to do thus far.
The bigger the project got though, the more often Hitfilm would just freeze. This usually happened when navigating around in the timeline or when zooming the timeline. The dreaded loading cursor would appear and when clicking anywhere in the Hitfilm window, a small popup would show up telling me that Hitfilm doesn't respond anymore. Waiting doesn't seem to do anything, so it is fastest to just close Hitfilm and start it again. This will get rid of all the progress since the last save though...
It happens so often now, that it became practically unusable.
These are my specs:
Windows 10 Pro N - 64 bit (with the latest Media Feature Pack installed)
Intel i7-7700 @ 3.6GHz
GeForce GTX 1070
Video Files are stored on an HDD due to size. OS and Hitfilm itself are installed on the SSD.
The video files are .MOV files coming from a Canon EOS 600D. The latest Quicktime player is installed as well.