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Why are slow jQuery animations choppy?

I'm having a hard time googling this issue because most of the things I can find are about animations that are supposed to be fast but are acting slow. My question is regarding an animation that I want to have a long duration but still be smooth.
I've created this jsfiddle to demonstrate the issue: http://jsfiddle.net/93Bqx/
I'm trying to make an element slowly move to another position over time. But the animation is very choppy.
Basically, it boils down to something like this:
$elem.animate({
left: x,
top: y
}, someLargeNumber);
I'm wondering if the problem is that the animation is so slow that each step is less than a pixel and so it is rounding them to either 0 or 1 making it appear to drop frames and then move all at once. But I don't know how I would check or fix this.
Is there a better way to be doing slow animations so they're smooth? I had a similar one created with CSS3 and translate(x,y) that was smooth but unfortunately I need more flexibility than I think I can get with CSS.

I guess it's the inevitable bargain with doing animation programmatically.
Maybe try a framework specialized in animation like:
http://www.greensock.com/gsap-js/
but adapting the animation to CSS would be best.

It's not much smoother even using a CSS transition.
I added the Transit jQuery plugin to test a CSS transition instead, and it looks almost the same.
Your code with minor fixes: http://jsfiddle.net/thirtydot/93Bqx/5/
Same code but with Transit added: http://jsfiddle.net/thirtydot/93Bqx/6/.
I think this is a limitation of the fact that (most?) browsers don't do subpixel rendering. As you mentioned, the x and y of the element is rounded after every step of the animation, and it's this rounding that causes the unsightly "jiggling" effect.
The CSS transition version does look noticeably better for less pathological test cases. Read this for more information: http://www.paulirish.com/2012/why-moving-elements-with-translate-is-better-than-posabs-topleft/

I think it has something to do with how often you move an element. For example, if you move the object once every second, it will seem choppy. Try decreasing the amount of time between each move as well as decreasing the distance between each move. See http://jsfiddle.net/2K9xP/ for an example.
So we have...
var duration = Math.round(10 * distance);
instead of...
var duration = Math.round(1000 * distance);

Repaint slowdown with CSS via Javascript in webkit browsers

I've been working on a slideshow script that uses CSS3 transitions, or jQuery's animate when they are unavailable. I've created a custom function to do the slide animations, which does so appropriately. Everything seemed to be working fine, but I've hit a major snag during testing.
For one reason or another, there is an large delay applying the jQuery CSS before and after the transition on large slideshows. For example, the slideshow in the link below is around 9900 pixels wide (container width, most of which is hidden). The container is maneuvered to display the appropriate slide, using CSS3 transition and transform properties. The delay occurs applying the CSS between lines 75 - 82 in the paste below. In particular, applying the 'transition' CSS causes the problem. Add the 'transition' CSS to the stylesheet (rather than applying it with JS), and delay disappears. This isn't really a solution however, because we only want to use CSS3 transitions on specific properties, that can vary (using 'all' in the stylesheet would transition some CSS that we don't want to animate, but change regularly).
Animation function:
http://pastebin.com/9wumQvrP
Slideshow Demo:
http://www.matthewruddy.com/demo/?p=2431
The real problem is with iOS, in which the slideshow (and even the browser sometimes) becomes completely un-usable. I can't pinpoint any errors, and have really exhausted my knowledge of debugging JS. I'm sure it is related to this section of the function after playing around a bit, and disabling CSS3 support within the plugin altogether removes the problem completely.
I'm completely stuck, and really appreciate any help anyone can give.
--- Edit ---
I've tried applying the CSS with native Javascript rather than jQuery's .css function. Same results, no better performance. Also worth noting that this isn't happening at all in Firefox, and seems to only be a problem with Webkit browsers.
Anyone with a solution, would happy to make a donation towards a few beers! I really cannot figure this out!
--- Second Edit ---
Ok, so been debugging and I can see that the slowdown is caused by the browser repaint cycle that is taking a very long time. Is there a better way to handle this that the way it is already doing? Positioning the element absolutely is a known way to reduce repaints, but that isn't really working because the slideshow is responsive. Absolutely positioning the slide images or the slides themselves causes it to collapse.
--- Third Edit ---
A day later, and I've made some progress. Adding 'transition: all 0s ease' to the elements stylesheet CSS has gotten rid of the repaint caused by adding the inline CSS transition property via the custom animation function mentioned in the original post. This causes a significant performance gain, especially when removing the inline CSS transition property when the transition itself has finished.
Good stuff! However, now there is still a slowdown when the inline CSS translate is being removed (that was used to create the hardware accelerated transition effect itself) after the transition, and the left positioning is being applied. When the two happen together, there is a slowdown.
Breaking them up into two separate tasks (the translate removed, then the left position added in a setTimeout with no time specified), again gets rid of the repaints = performance gain, and looks likes problem solved. But sometimes, the CSS transition property isn't get negated fast enough, and the translate removal gets animated. No good, and don't know where to look next to work around it.

I think the problem is you're loading HUGE images :)
They are too big for the container you have them in, so you scale them down, which is even more resource intensive.
Try resizing them.

First of all congrats for your debugging!
I have been working on the exact same stuff lately and found out that ios devices don't support a large number of images positionned in the same page. It causes crashes and the only solution I found was removing elements instead of just hiding them. The downside is that removing and appending elements causes lags so you have to do it cleverly, when your transitions are done. I thought the best way to go was keep 3 or 5 images in the DOM and replacing the rest with thumbnails of the images, resized to fit the original. When transitions are done, I'd just put the large images back into place...
Hope this helps you a bit on the ios problem at least...

After spending some time analysing your code TimeLine with Chrome Dev Tools, I believe there's some optimization you could do.
As far as I can tell, every single one of your 16 images gets fully repainted every time an animation is requested. This seems quite obvious to me, as there are 16 images in your example, and the Chrome Dev Tools reports 16 long "Paint" executions every time in hit "Next".
In my humble opinion, you should figure out a solution that considers only translating two images: the one you want to hide and the one you want to show. So, consider please, not moving the rest of the images and, instead, leaving them all side-by-side to the shown image.
One more thing, using scaled down images is probably making the paint cycles quite longer. Avoid them whenever you can.

Well, think I've managed to figure it out! Just so you know, original post links don't reflect the changes as I've done them on my localhost environment.
Absolutely positioning the slides container has fixed the problem that was occurring with repaint speeds after the transition had taken place (whilst applying CSS properties). Obviously taking them out of the DOM has done the trick, allowing painting to take place much more efficiently.
I originally didn't try this too much because I knew this would add a lot of work to the resizing functionality. I had originally intended to not resize at all in JS, and rely on percentages to do the dirty work. Absolutely positioning the container would cause the slideshow viewport to collapse, rendering the native resizing useless.
However, I was already having problems with sub-pixel rendering in other browsers anyway, so I guess it was time to bite the bullet and rely on fixed pixel values. I then used JS to handle the resizing, using the window resize event. All seems good, however the slideshow was still collapsed due to the positioning. Assigning height values wasn't working correctly, so was at a bit of a loss.
Thankfully, I came across a neat little trick of setting the 'padding-top' of the slideshow viewport to a percentage value, dynamically calculated (desired slideshow height, set in the settings panel for this script, divided by desired width). As padding-top percentages are relative to the width of the element, this did a great job of providing responsive height and correcting the viewport again (no longer looking collapsed).
Here is some info on using padding-top for responsive elements that maintain aspect ratio. Great little trick: http://f6design.com/projects/responsive-aspect-ratio/
All is good now, and things are working well in iOS and webkit browsers. Everything is extremely quick and working as it should. Four days later, and it is finally figured out. Not happy about having to resort to JS for resizing, but I guess it was always going to happen due to percentage inconsistencies between browsers. Lots of decimals = no good!
Thanks to all who tried to point me in the right direction. Definitely got me thinking, and learned a lot of debugging skills that I can use again to make sure transitions are performing well. Thanks again!

not sure if this helps or not but I noticed you use 3d translation - I would think a simple 2d translation would be enough especially since your third parameter is 0 and might accelerate the issue, also go with fewer images as Armel L. suggested, don't have an iphone to test though... alternatively, this is a solution I used before css3 but should still work move the element containing the images using javascript by modifying left (?and top - the demo only moves left and right though? without the transition effects) and this way you can fine-tune the refresh rate which I think might account for the slowdown... you can go as low as 18 fps without anyone noticing, might even be good enough with just 16fps

I had this when I was first designing a magazine carousel-style page device.
If you have a series of images within a long "tray", even if they are not within the viewport, they will still take up ram, and you can effectively have five or so before leaks and nastiness begin to happen.
What I found works is "hiding" them ... But make sure they take up the physical space necessary.
What I also found worked was that one could make the 'previous' current and 'next' image are visible and move the tray, 'unhiding' them as they reach those three positions.
In my own system, I skipped the 'tray' holding e images and only had them at -100% width, 100% width and the current one a 0.
I never had much luck with the typical long-tray carousel with large scale background images... Especially with css3 acceleration.

Why are [my] CSS3/jQuery transitions so imperfectly smooth, and how do I make them more smooth?

As much as I've searched for information about this all over the internet, I can't find anything about it, so I've come here for help.
What's been bugging me: That no matter which method I use -- a jQuery .animate, or a css3 transition, [my] animations don't appear to be perfectly smooth. I didn't understand why they appear this way at first, and it's so subtle I ended up having to do some video capping to prove it. But it's definitely there -- the animations are juttery. Sometimes a frame happens too fast, and sometimes too slow.
Flip it back and forth six or seven times, and you'll hopefully see what I'm talking about.
I can understand this with jQuery -- JS execution isn't perfect. A quick profiling shows that indeed, when using jQuery anim, some frames get triggered too soon and some frames are late. But with CSS3?
What do people do to solve this problem?

I am moving the container using the margin-left CSS property and .animate of jQuery and is pretty smooth. Use the arrow keys to use it (left and right)
The current version of that project its now full of images, text, iframes and is still smooth.

Set this JS before your code:
jQuery.fx.interval = 100;

Having trouble with fadeIn and fadeOut in IE8 with jQuery

Here is my site: http://www.dreamweddinggroup.com/redesign and I'm having a hell of a tough time figuring out why in gods name my fadeIn, fadeOut and corner() functions won't work in IE8. They were working for a time, but now they have broken and I can't for the life of me figure it out. Can anybody see anything that would cause the problem here?
To see what I'm talking about, if you were to click on the "About Us" link at the bottom of the page, you should see the text fade in. Then if you were to click on "Why Dream Wedding Group", the "About Us" text should fade out, and when it fades back in, you would see the new text.

Hey I was having the same trouble. I was trying to fadeOut an IE image and fade something new in like so :
$(".edit_photo_link").click(function(){
$(this).fadeOut("slow", function(){
$(this).next(".throb").fadeIn("slow");
});
});
Which wasn't working. But the FadeIn was! So guessing that this was processor getting eaten up by IE8 (not IE7), I just changed it to this :
$(".edit_photo_link").click(function(){
$(this).fadeOut("slow", function(){
$(this).hide();
$(this).next(".throb").fadeIn("slow");
});
});
And IE8 users don't get that extra loving of animation.

I had similar problems with a stack of absolutely positioned divs. I wanted to simultaneously fade one out and fade one in. Code that worked fine in FF/Safari would not work in IE8: The fadeOut() wouldnt fade, only the fadeIn().
I found solution was to use CSS to set the z-index of the element to be faded-in to be at the top of the stack:
$('#fadeoutdiv').css({zIndex:90}).fadeOut(2000);
$('#fadeindiv').css({zIndex:99}).fadeIn(2000);

I'm finding that IE8 has terrible performance using fadeIn myself with just a small image or text area. I think the engine is basically very bad at alpha blending! Because you're trying to fade fullscreen images, the performance is so slow that you just don't see the fade. In my case, I'm seeing CPU usage rocket to between 50% and 100% even on fairly powerful desktop with a decent graphics card. My client is having problems because every time this fade happens (every 5 seconds or so), video that is also playing starts skipping and being generally unstable.
Another site I'm working on is http://www.urstreams.com , if you hover over the boxes you will see a description appear also using fadeIn. If you mouse over all the boxes at once, so all the descriptions are appearing and disappearing at the same time, all the animations grind to a halt and CPU again rockets skyward.
Bit of a nightmare really, but at this stage I would recommend against any alpha blending animation in IE. The common theme in all these cases seems to be that blending is occurring over images. Perhaps this is the problem, as common jQuery samples and possibly tests / benchmarks tend to focus on basic scenarios such as plain text appearing over plain background tests?

I too have noticed this phenomenon with IE 8, though it seems to occur no matter what my element is floating above. I had an empty 4x4 px DIV that i was fading in and out on an interval (interval at 400ms, then element.fadeIn(100).fadeOut(500)) to debug element positioning and it was completely obliterating one of my cores! It took me a while to figure out why IE was constantly hitting 50% CPU while Chrome and Firefox barely broke a sweat -- I figured I had a rogue greedy loop somewhere until I scanned across my interval.
Fire up IE and your task manager and head over to http://www.hv-designs.co.uk/tutorials/jquery/all.html for a little test. Sort your running processes by CPU desc and watch IE rise to the top on every test (20-40+% of my 1.2 GHz dual-core Intel SU2300 for the duration of the fade +/- a few hundred ms), even for the simple text paragraph! Running the same test in Firefox or Chrome doesn't even break 10% usage for me.

Jquery animate problem

I have the weirdest of problems.
I have a jQuery function that animates the result bars of a poll.
function displayResults() {
$(".q_answers1 div").each(function(){
var percentage = $(this).next().text();
$(this).css({width: "0%"}).animate({
width: percentage}, 'slow');
});
}
As you can see it is a simple animation that elongates a couple of divs. It works OK until I embed it on my main page. The problem seems to be that there is too much OTHER content that breaks the beauty of the smooth animation. I was thinking of me being lame in implementing the JavaScript, CSS etc. but after a couple of tests and reverse engineering I found out that THE MORE CONTENT (images, text, video) I HAVE ON THE PAGE, THE WORSE THE QUALITY OF THE ANIMATION IS. I can only guess what the reason is... I really like my animation :)! Appreciate the help!
This demo shows how it should look like. I get it to work like this when the page has less content on it. By bad quality I mean not smooth flow of the bars. The worst case is when the bars appear in their final width in an instant.Tested it on Mozilla and Chrome and IE7 - no difference.
Edit: It seems that without the actual examples your hands are tied so here is something to work on. Just look for the red border, pick one answer and click the button. The language is Bulgarian if you are wondering.
A desirable behavior here
I can live with that here
Starting to look weird here
I don't get this here
If all of them look the same to you then my computer is to blame and I don't have to worry about this particular problem anymore, which already took 2 much effort. Use Mozilla if possible.
Edit 2: I found this SO answer that answers some of my questions about the animate() function and how it works, but the problem remains unsolved, at least for my computer.

How much content are we talking here?
If the page is large enough, the browser engine may simply not have enough power to re-render the contents quickly enough to provide a smooth display.

The way jQuery does it's animation is that it periodically updates inline CSS attributes. If the elements you're changing style's of are floated or have other complex interactions with the other elements on the page then the animation wont be smooth.
In short, put less stuff on your page. You might also attempt some sort of iFrame solution or switch to using flash to display the results.
This is just a limitation of the system, unfortunately.