UserAgent: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.22 Safari/537.36

Steps to reproduce the problem:
1. open https://demo.synology.com/en-us/dsm; and start DSM demo
2. open chrome taskmanager or windows taskmanager. see abnormal CPU usage (this page without activity use same CPU resource than youtube to play vp9 720p video) (10%CPU load intel corei5 5500, more 50%load with old core2Duo T5xxx)
3. open dev-tool to search why this cpu usage

can found high style recalc/s, but when open animation.. nothing is displayed (must wait 30sec)
 * https://youtu.be/cmDEKYusRM0

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Next test after block DIV with uBlock origin extension with personal filter:
 a81.dsmdemo.synology.com##.x-box-item > .thumb_conv_progress_desc > .syno-percentage-cmp.sds-ux-progressbar > .percentage-cmp-hbar-background
or remove previous source code with animation never stop.

4.open FileStation (on DSM demo interface)
5.move one file to another folder
6. check with dev-tools, CPU load and style recalc/s increase to 60 and not stop.
=> animation tool not display animation (wait 3min without result)
 * https://youtu.be/2DGWPlNTqbY

Use firefox, inspect source, clic animation.. immediately firefox dev-tool display zebra_move animation for step 3 and 6.
 * https://youtu.be/P2WD3cCGxc8

What is the expected behavior?
It's one request to have same as firefox to see immediately real time calculated animation css.

What went wrong?
no option to see realtime animation. Must wait more 30sec (or never see it) before see zebra_move animation with chrome animation dev-tool.

(and not sure it's normal that Chrome calculate zebra_move when this animation is not in display zone and not visible (but it's same with firefox, I already reported this problem to Synology but they do not want to understand because it only represses 3% CPU on AMD Rysen 7))

Did this work before? No 

Chrome version: 70.0.3538.22  Channel: beta
OS Version: 6.1 (Windows 7, Windows Server 2008 R2)
Flash Version: 

sorry for my very average english, that's why I linked screencast, hoping it helps.