With or without starship, one problem I have with zsh prompts is that when I press Enter, there is still a visible delay where for a fraction of a second, the cursor moves to the beginning of the next line.
This makes a nasty "flashing" effect.
If I keep Enter pressed, the cursor is permanently visible at offset 0 in the lowest line.
If the prompt is ultra-fast (e.g. plain root shell prompt on zsh), it happens less (e.g. only 50% of cases), but as soon as the prompt does anything, it's very visible.
I observe this with many terminals (gnome-terminal, wezterm, kitty, alacritty, xterm).
The only terminal I tried that doesn't have this problem is urxvt, where it looks perfect.
input_delay doesn't seem to address this in general: Even when set to 50 (which is very noticeable), the cursor on the next line just appears with some delay.
Interesting, In zsh I experienced the exact behavior you described and setting input_delay to 10 completely resolved it. To be fair, when testing my PS1 was simply '%m$ '.
I just benchmarked 'starship prompt' and when in a directory managed by git, it can take well over 10ms. I imagine with a more advanced configuration it would take even longer. urxvt must be doing something special.
This makes a nasty "flashing" effect.
If I keep Enter pressed, the cursor is permanently visible at offset 0 in the lowest line.
If the prompt is ultra-fast (e.g. plain root shell prompt on zsh), it happens less (e.g. only 50% of cases), but as soon as the prompt does anything, it's very visible.
I observe this with many terminals (gnome-terminal, wezterm, kitty, alacritty, xterm).
The only terminal I tried that doesn't have this problem is urxvt, where it looks perfect.
Video repro: https://nh2.me/flashing-cursors-on-newline.mp4
Why, and is there a way around it for those other terminals?