Someone asked Why did moving the mouse cursor cause Windows 95 to run more quickly? over on Retrocomputing.

Raffzahn's answer mentions that it's also possible to observe the effect of things running faster when the user moves the mouse whilst scrolling through a large text file. Nowadays I don't scroll through text files anymore (because I flip through pages or search for a string that's close to the location I'm looking for), so over the years this knowledge got lost on me. But I remember always doing this when working on a Windows XP computer.

However, when I subsequently tried it on my 2019 computer running Linux 4.15, I still found the effect to exist. This is despite only one core going up to 50%, none going above that, and all of the others just idling away. I can get one core go over 90% and sometimes reach 100% by wiggling with my mouse.

Why is it still like that, even if many cores are available and even the one that's serving the text editor is only busy half of the time?

  • I've noticed this effect too. You used to need to do this to get Excel worksheets to scroll quickly, though I've noticed it working in fewer programs as time goes on. – Twisty Impersonator Jul 1 at 21:51
  • I agree with Christophers answer. I'm not sure if CPU consumption is still relevant for UI. Most browsers or libreoffice support GPU rendering most PCs have a better one than in 1995. The scrollbars "scrub" or "thumb" is indicating how much the current page/view represents in relation to the entire document. If you need to scroll really fast, just hold the scrub/thumb with your mouse and move it up/down or left/right to navigate to a certain spot in the document. The page-up/page-down keys on your keyboard will move your view pagewise with a little overlap. – Michael D. Jul 1 at 22:23
  • @MichaelD. I can make the load on a single core of my Ryzen 5 2600 go up to over 90% and sometimes even reach 100% if I wiggle fast enough when scrolling though a large file via Kate (standard graphical text editor of Kubuntu) by dragging a selection. – UTF-8 Jul 2 at 19:43

Scrolling is an interaction with a human being. It would be counterproductive to have a thousand-page document, scroll really fast, and arrive at page 600 within a second. Scrolling is designed to that the human eye can read headlines and see pictures and other big cues, and stop where a landmark is recognized.

If the user knows approximately how far in a document to go, they can grab the scroll bar on the side of the window and go straight to it. Similarly, they can search, use a chapter list / bookmark function, or use hyperlinks in the text.

But scrolling is fundamentally an interaction with the human being, and therefore going faster than the human can react to is not useful.

  • I don't think the OP has use of the scroll bar in mind, but rather scrolling by dragging the selection cursor with the mouse. – Twisty Impersonator Jul 1 at 22:23
  • @TwistyImpersonator Maybe you could impersonate me with that knowledge cuz you're right. – UTF-8 Jul 2 at 19:41

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