1451320 - Horrible sluggish cursor movement in textareas

Status: RESOLVED DUPLICATE of bug 1448818

(Core :: DOM: Editor, defect)

Description

[TGOS]

Attachment: firefox-sluggish-cursor.mp4

When moving the text cursor with left/right arrow key, the cursor is supposed to be shown permanently (non-blinking!) and jump from character to character. Instead it will often perform huge, sluggish jumps, being invisible in-between. This seems to have to do with the amount of text in a text field; once it is over a certain limit, the cursor movement becomes horrible slow. For demonstration purposes, I copied the GPL 3 to this text field and then made a screencast to demonstrate the issues. First I hit the left arrow key 4 times and then I keep it pressed (and no, it's not the low frame rate of the video causing this effect, that's exactly how it looks like on my screen).

Firefox 60.0b9 (64-bit)
Mac OS 10.13.3
MacBook Pro (Retina, Mid 2012)

Comment 1

[Makoto Kato [:m_kato]]

This depends on retained display list.  layout.display-list.retain=false is workaround.