My main monitor is 144Hz. An easy way of seeing the current FPS is wiggling the mouse - the movement in 144 FPS is much smoother than 60 FPS, and this is very noticeable.

While using Terminal, the FPS constantly drops, and moves between low FPS and full 144 FPS. I can't tell if it drops to 60 FPS or a different amount, but it's way lower than 144 FPS. Wiggling the cursor while typing shows this problem well.

It seems like every interaction with the Terminal can cause the FPS to "flip" between low and high: Focusing on the window, typing, etc. Sometimes waiting ~3 seconds is enough for the FPS to switch back to high.

Graphics card is an Nvidia GTX 1080 Ti and monitor is an Asus PG279Q.

C:\WINDOWS\system32>ver

Microsoft Windows [Version 10.0.18362.86]