Big Sur terminal sometimes 5-second lag, 16in macbook pro
Update: confirmed issue still happens as of macOS 11.2 RC3
Exact same behavior here on a 16" 2019 MBP, starting from when I updated to macOS 11.0 and still occurring as of 11.2 beta 2.
Able to reproduce "on demand" by typing "ls" repeatedly in both iTerm2 as well as the built in terminal.app.
Root cause seems to be the Intel graphics driver, as disabling graphics switching or connecting an external monitor (which forces discrete graphics) eliminates the issue at the cost of battery life.