Thanks for filing the issue!

Able to reproduce the issue on reported chrome stable version 69.0.3497.81, Dev 70.0.3534.4 and canary 71.0.3543.0 using Windows 10 and Mac 10.13.1, when downloading the builds from https://www.chromium.org/getting-involved/dev-channel
Note: Couldn't check the Linux behaviour as we are facing few technical difficulties while launching the game.
But the same issue isn't seen when checking on builds(signed/unsigned) downloaded from build repository. In such case, it's out of scope for us to triage further to find the regression range. Hence, tentatively marking it as Untriaged.

Providing the list of the variations from Beta installation of 69.0.3497.81 where the issue is seen.

Variations	
c134752e-95b424ac
d01ab0d3-a1f91ada
3e006338-f23d1dea
b7e2524c-3f4a17df
a6674cf-4f295bf2
b1681d28-803f8fc4
cc20827f-dea79bd3
8fe39baa-3f4a17df
38eb801c-3f4a17df
c27fec31-2d5b6ed9
7c1bc906-8122a015
47e5d3db-3d47f4f4
125b7f68-65bced95
d442dfb7-eeca42f7
9ca1387e-65bced95
41e765a5-f23d1dea
1149accc-65bced95
4dc30737-b8a5ea08
a582a1b8-ad75ce17
8ee5ed19-ca7d8d80
74658432-ca7d8d80
3042ad4b-ca54bb47
e56c5101-ad2fa222
249dd49a-28165b59
44827ee5-43146c13
edbcf7c5-961c461c
5485fc4d-3f4a17df
de47491b-33c3eba5
93731dca-e89d496c
9e5c75f1-6943e6a2
2594bdf4-f1cfee3a
2b86fd96-f23d1dea
45df16ca-ca7d8d80
4ea303a6-9fba3b4c
6e6e0c7e-3f17a7d8
d92562a9-65bced95
7aa46da5-c946b150
4da5ae82-f23d1dea
de52c077-65bced95
6973a1cf-3f4a17df
cc54eb06-3f4a17df
58a025e3-36e97b2c
ad6d27cc-1627c3cf
df072bba-9a6c5085
f242806f-5810b593
4bc337ce-535cb40a
9a2f4e5b-3fe9c4dc
494d8760-52325d43
3ac60855-3ec2a267
f296190c-c4f4d776
4442aae2-6e597ede
ed1d377-e1cc0f14
12e17bc5-e1cc0f14
75f0f0a0-6bdfffe7
e2b18481-e1cc0f14
e7e71889-e1cc0f14
5e60f31d-1410f10
3a4029d-ca7d8d80
94e68624-803f8fc4
cc73f8a1-a2d707c6
10a311eb-f23d1dea
8834fcca-cf4f6ead
81c6897f-672c76c9

Not 100% sure but suspecting VideoSurfaceLayer.

mlamouri@: Is this enabled via Finch on Beta/Stable channel? 

kamiljoz@: Does disabling #enable-surfaces-for-videos under chrome://flags makes any difference?

ajha@, what makes you think it's VideoSurfaceLayer given that the game doesn't seem to be using any video.

 ajha@: nope, disabled #enable-surfaces-for-videos via chrome://flags and attempted going through the same STR. Still pretty janky. Also restarted Chrome after disabling just incase, same results.

Thanks  kamiljoz@ for the confirmation.

As per C#3 the issue seems to be happening on canary/dev/beta/stable channel builds downloaded from https://www.chromium.org/getting-involved/dev-channel but doesn't repro on signed builds downloaded from build repository so probably this is related to some experiment or Finch trial on these channel.

Somehow disabling #enable-surfaces-for-videos worked fine for me on first run and as VideoSurfaceLayer featured in Variations from C#4 hence suspected the same. But this looks unrelated due to no video on the page+issue persists as confirmed C#6. Not 100% sure about the other root cause of this.

Will try a bisect of this based on CPU usage and Energy Impact under Activity Monitor as these seem to spike considerably when playing this game.

similar issue:
https://bugs.chromium.org/p/chromium/issues/detail?id=880901&can=2&start=0&num=100&q=chrome%2069&colspec=ID%20Pri%20M%20Stars%20ReleaseBlock%20Component%20Status%20Owner%20Summary%20OS%20Modified&groupby=&sort=

This is showing really inconsistent behavior when trying to bisect. Issue is not repro consistently on downloaded signed/unsigned build whereas this is easily reproducible on latest beta/stable(69.0.3497.81) build downloaded from https://www.chromium.org/getting-involved/dev-channel as tested on Windows-10.

kamiljoz@: Could you please check if the issue is seen on Dev and Canary or not? You can download the same from here https://www.chromium.org/getting-involved/dev-channel, also please confirm whether there is any effect on jankiness when you turn off the hardware acceleration.

Apprecite your help!

WIW, I can reproduce the regression in Beta but not Canary on Mac.