firefox at 100% CPU utilization

[A]

solarmoviez.ru pegs the CPU at over 100% and slows the machine significantly. Screenshot attached.

Description: Ubuntu 16.04.6 LTS
Release: 16.04

firefox:
  Installed: 66.0.4+build3-0ubuntu0.16.04.1
  Candidate: 66.0.4+build3-0ubuntu0.16.04.1
  Version table:
 *** 66.0.4+build3-0ubuntu0.16.04.1 500
        500 http://us.archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu xenial-security/main amd64 Packages
        100 /var/lib/dpkg/status
     45.0.2+build1-0ubuntu1 500
        500 http://us.archive.ubuntu.com/ubuntu xenial/main amd64 Packages

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: firefox 66.0.4+build3-0ubuntu0.16.04.1
ProcVersionSignature: Ubuntu 4.15.0-47.50~16.04.1-generic 4.15.18
Uname: Linux 4.15.0-47-generic x86_64
AddonCompatCheckDisabled: False
ApportVersion: 2.20.1-0ubuntu2.18
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: apb 15542 F.... pulseaudio
 /dev/snd/pcmC0D0p: apb 15542 F...m pulseaudio
 /dev/snd/controlC0: apb 15542 F.... pulseaudio
BuildID: 20190506102248
Channel: Unavailable
CurrentDesktop: Unity
Date: Wed May 8 21:12:37 2019
ExecutablePath: /usr/lib/firefox/plugin-container
Extensions: extensions.sqlite corrupt or missing
ForcedLayersAccel: False
IfupdownConfig:
 # interfaces(5) file used by ifup(8) and ifdown(8)
 auto lo
 iface lo inet loopback
IncompatibleExtensions: Unavailable (corrupt or non-existant compatibility.ini or extensions.sqlite)
InstallationDate: Installed on 2018-09-20 (230 days ago)
InstallationMedia: Ubuntu 16.04.4 LTS "Xenial Xerus" - Release amd64 (20180228)
IpRoute:
 default via 192.168.0.1 dev enp4s5 proto static metric 100
 169.254.0.0/16 dev enp4s5 scope link metric 1000
 192.168.0.0/24 dev enp4s5 proto kernel scope link src 192.168.0.3 metric 100
Locales: extensions.sqlite corrupt or missing
MostRecentCrashID: bp-1c6ff3ca-51b4-47e8-b009-e5feb0190429
Plugins: Shockwave Flash - /usr/lib/flashplugin-installer/libflashplayer.so
PrefSources: prefs.js
Profiles: Profile0 (Default) - LastVersion=66.0.4/20190506102248 (In use)
RunningIncompatibleAddons: False
SourcePackage: firefox
SubmittedCrashIDs:
 bp-1c6ff3ca-51b4-47e8-b009-e5feb0190429
 bp-cbd10a93-2bd7-46a7-b905-6df710190425
Themes: extensions.sqlite corrupt or missing
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 06/17/2016
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: P1.60
dmi.board.name: 970M Pro3
dmi.board.vendor: ASRock
dmi.chassis.asset.tag: To Be Filled By O.E.M.
dmi.chassis.type: 3
dmi.chassis.vendor: To Be Filled By O.E.M.
dmi.chassis.version: To Be Filled By O.E.M.
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrP1.60:bd06/17/2016:svnToBeFilledByO.E.M.:pnToBeFilledByO.E.M.:pvrToBeFilledByO.E.M.:rvnASRock:rn970MPro3:rvr:cvnToBeFilledByO.E.M.:ct3:cvrToBeFilledByO.E.M.:
dmi.product.family: To Be Filled By O.E.M.
dmi.product.name: To Be Filled By O.E.M.
dmi.product.version: To Be Filled By O.E.M.
dmi.sys.vendor: To Be Filled By O.E.M.