I have a new system. Windows 10, i7, AsRock390 board, 64GB of tested memory, GeForce 1060, 650 watt PSU, SSD for programs, etc..
I have tried everything as far as I know. I have looked at many posts of people who have had similar issues. I cleared the cache by closing the program and ctrl/shift double click shortcut on desktop. That function worked but solved nothing. I restored to default settings. I even reinstalled the software. I am not even using any plugins so far. I even went into preferences and disabled all additional VST's. No change.
If I start a new project it will work fine but once I get more than 4 or so video files going it starts to react slowly then freezes. Once it freezes and I restart the project it will continue to freeze. All I am doing is a very simple project that has videos fading into each other using the automatic fading function when sliding files together. I'm not even close to rendering yet.
I record music regularly with multiple effects and virtual instruments running at once and this system doesn't flinch at all. I also occasionally run music visuals software which can be resource intensive with no issues. No resent hardware changes have been made. No programs other are open during these issues. All updates have been done including this program and the 1060.