I don't know about others, but I for one have stopped using Lightroom for anything related to my video. Lightroom is resource hungry as it is on still images. It's just easier to use video software to work with video.
Generally, I am with you on this, but I still try and use Lightroom as my asset management tool, and due to my workflow, I like to keep a single "master" application for managing files. I tried a few other apps, but some of them wouldn't work with video, and others didn't have my output requirements (video conversions to certain folders) so I am still using Lightroom. I would like to blame the network storage but two things stop that:
1: using any other app to play the video from the NAS works perfectly
2: playing local SSD video through Lightroom work pretty badly too.
Maybe the answer is stop using Lightroom for video asset management.
You might try doubling your RAM to 16 GB to see if that helps. But that's kind of a gamble if the only purpose is to improve video performance in Lightroom. I don't shoot a lot of video, but when I do I use Premiere Pro. I'm using an i5 computer with 8 GB RAM and Premiere Pro stutters a little bit while I'm editing, but the exported finished video plays just fine. 16 GB of RAM are recommended for Premiere Pro, but my computer will only accept 8 GB. Thinking about getting a new computer, but not very seriously right now.
Lightroom isn't really optimized to play video. I have 32GB RAM but LR still doesn't really like vid. Premiere would be a better bet for working on video.