quicktime

I'm using QT7 Pro as part of my workflow in a virtual machine. (If there was an equivalent to QT7 Pro on 64 bit I'd take it.) Host machine is MacBook Pro 16 32GB RAM with AMD Radeon Pro 5500M 4GB VRAM. Any tips on optimizing performance? Even at 8GB RAM with 2 processors (as recommended)...

My default app setting in macOS for MP4 files is QuickTime, yet when I double-click an MP4 file, Photos in Win10 opens. How do I prevent Photos from hijacking the default setting even when QuickTime is set as default?