Firefox Portable edtion 69.0.3 is not working normally with bilibili.com video

Hi, there is a problem when visiting bilibili.com and can't play video smoothly from FirefoxPortable.exe.
It's stuck every 3-5 seconds and then the vision moves on then stuck again in a loop.
URL: https://www.bilibili.com/video/av71357702

But, it's ok when running firefox.exe from its install directory normally.
So is there any solution?