If I type “about:memory” into the internet address field of Firefox, then I get among others a button “minimize memory usage”. But I’ve also read that Firefox is known as a “Memory Monster” 🤪. VLC player can be used for streams too but some streams crash after a few seconds. I’ve read furthermore that Windows forces Firefox too rarely to free memory. There’s last but not least a recommendation to use the 32Bit version of Firefox even on a 64Bit operating system due to a lower memory usage.