network response very slow

For the last 48 hours all internet access has been extremely slow. Prior to that time there was no problem. I tried rebooting the modem but that only provided temporary relief. After the 3rd reboot I asked my ISP to replace the modem. That did not resolve the issue. I have two computers connected to the modem, a laptop running 15.04 vivid vervet kernel 3.19.0-22-generic which is connected both by Ethernet cable and wifi, which displays excessively slow response, and a desktop running 14.04 which is connected by Ethernet cable only which shows normal performance. There are also problems with the network manager app which frequently no longer appears when resuming from suspend and if it does appear shows no useful information and does not support connecting by wifi. These problems only started occurring about 48 hours ago, so I suspect the last package installed, which is webkitgtk.

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: libwebkitgtk-1.0-common 2.4.8-1ubuntu2
ProcVersionSignature: Ubuntu 3.19.0-22.22-generic 3.19.8-ckt1
Uname: Linux 3.19.0-22-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.17.2-0ubuntu1.1
Architecture: amd64
CurrentDesktop: Unity
Date: Sun Jul 12 18:11:19 2015
Dependencies:

PackageArchitecture: all
SourcePackage: webkitgtk
UpgradeStatus: No upgrade log present (probably fresh install)