UserAgent: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2824.0 Safari/537.36

Example URL:
http://waitbutwhy.com/2016/03/sound.html

Steps to reproduce the problem:
1. Open http://waitbutwhy.com/2016/03/sound.html, chosen because it contains several large and detailed gif animations over several pages. Observe that the gifs animate smoothly.

2a. Click and drag a gif in-place for several seconds, releasing on the page for no action.

2b. Scroll the page between drags if the effect is not yet apparent.

3. Observe that all animation halts for a few seconds during the drag, scrolling remains smooth.

4. Repeat 3+ times and all animations will be choppy, slow, or completely halted.

5. Refresh page, observe that animations are still degraded.

6. Middle-click or Ctrl+Click a gif to open it in a new tab. Animation is still degraded in new tab.

7. Close new tab, Ctrl+Shift+T to reopen closed tab. Animation is smooth in new tab.

8. Close original tab, Ctrl+Shift+T to reopen closed tab. Animation is smooth again in original tab.

This doesn't affect just gif animation, but page requests and other performance in that tab too, except for scrolling oddly enough. Induce it on that article, and then try to browse to other articles on the site by using MMB/Ctrl+Click into new tabs, the performance degradation will follow into the new tab, but left clicking a different article and going back to the original seems to clear the issue.

What is the expected behavior?
Smooth animation in most cases, at least after completing a drag action.

What went wrong?
Runs like a Ubisoft port.

Does it occur on multiple sites: Yes

Is it a problem with a plugin? No 

Did this work before? N/A 

Does this work in other browsers? N/A 

Chrome version: 54.0.2824.0  Channel: n/a
OS Version: 6.1 (Windows 7, Windows Server 2008 R2)
Flash Version: Shockwave Flash 22.0 r0