Web Content spent more cycles on NULL pointer

[asu]

For this test run kernel 4.6.2 modiffied.
1.Run from terminal sudo perf record -ag when firefox running on youtube
2. Stop perf process and read the result, result is belllow:

Samples: 26K of event 'cycles:p', Event count (approx.): 9427386496
  Children Self Command Shared Object Symbol
+ 9.06% 0.00% Web Content [unknown] [.] 0000000000000000
+ 5.29% 0.00% Web Content [unknown] [.] 0x0000000000841f0f
+ 3.86% 0.00% Web Content libxul.so [.] 0xffff80a98562dc70
+ 3.03% 0.00% Web Content libxul.so [.] 0xffff80a9855affd0

On most time access on NULL pointer or unknown symbol.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: firefox (not installed)
Uname: Linux 4.6.2+ x86_64
ApportVersion: 2.20.1-0ubuntu2.10
Architecture: amd64
CurrentDesktop: MATE
Date: Tue Aug 1 21:07:17 2017
InstallationDate: Installed on 2016-04-29 (459 days ago)
InstallationMedia: Ubuntu-Studio 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
SourcePackage: firefox
UpgradeStatus: No upgrade log present (probably fresh install)