keyboard response slowly

[arm_lover]

when I input some words in the terminal or browser. the keys echo very slowly.
I have to reboot the system. but after some hours, the issue reproduced.
I use the ubuntu18.4 now, but Ubuntu16.4 I used before have the same issue.

~$ lsb_release -rd
Description: Ubuntu 18.04.1 LTS
Release: 18.04

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: evince 3.28.2-1
ProcVersionSignature: Ubuntu 4.15.0-34.37-generic 4.15.18
Uname: Linux 4.15.0-34-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.3
Architecture: amd64
CurrentDesktop: Unity:Unity7:ubuntu
Date: Sun Sep 30 10:29:39 2018
InstallationDate: Installed on 2018-05-14 (138 days ago)
InstallationMedia: Ubuntu 16.04.4 LTS "Xenial Xerus" - Release amd64 (20180228)
SourcePackage: evince
UpgradeStatus: Upgraded to bionic on 2018-09-17 (12 days ago)

[Daniel van Vugt (vanvugt)]

Can you please:

1. Run 'top' to see if any process is using very high CPU when the response is slow; and

2. Run 'lspci -k' and paste the output here.

[Launchpad Janitor (janitor)]

[Expired for gnome-shell (Ubuntu) because there has been no activity for 60 days.]