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Comment by darshan | Hacker News Reader

I'm pretty sure I mouse as quickly as anybody. It's just that the difference between 17 ms per frame and 33 ms per frame on my system only affects the smoothness of animations. There's no perceptible lag no matter how quickly I move things around.

View on HN

To add one more data point, I usually set my mouse sensitivity to maximum (people usually complain about how sensitive my mouse is when they borrow my computer), and while 30fps is fine for everything else, it's unbearable to me when mousing.

I just did a test: Over 5 seconds I moved my mouse to the top of my monitor and back down 15 times, which works out to 12000 pixels per second, or 396 pixels per frame - which seems about right for how far the mouse seems to jump per frame. For comparison, Chrome's Close Tab button is 15x15 pixels, and HN's upvote button is 8x7 pixels. Framerate really is the limiting factor for how long it takes me to move my mouse onto the kinds of click targets common in computers.

Another test: it takes around 6 seconds to close 7 tabs with a mouse in Chrome in 30fps, and 4 seconds to close the tabs in Chrome in 60fps.

So I think I've pinpointed the exact problem. There are two parts to moving a cursor to a click target: quickly moving the cursor in the target's general direction, and then slowly moving to its exact position. Both are much more unpleasant in 30fps.

Quickly moving in the target's general direction: it's a lot easier to track a 10x20 pixel cursor when it's jumping 150 pixels per frame than if it's jumping 300 pixels per frame. (These are my own numbers, judging by people's reactions to my mouse sensitivity settings, it's likely yours would be lower.)

Slowly moving to the target's exact position: if the click target is 8x7 pixels like HN's upvote button, I can't move any faster than 2-3 pixels per frame, which is obviously half as fast in 30fps as in 60fps.

Well, if you mouse that fast then your use-case is similar to the aforementioned twitch-based FPS games.

> There are two parts to moving a cursor to a click target: quickly moving the cursor in the target's general direction, and then slowly moving to its exact position

This is a pretty basic usability issue and one of the reasons we put clickable things on the edge of the screen if we can.