Problems with Fedora 20

[Roger]

Couple of things seem to have gone awry.

I think Ubuntu update to 14.04 has messed around with Fedora 20 grub 
boot because booting now  takes for ever and defaults to  Ctrl D to 
Continue or root password for maintenance, then takes 30-50 seconds to boot.

2nd, With the  latest updates and kernel-3.15.5-200.fc20.x86_64 
something seems wrong. The machine used to be quite fast but now is very 
slow.
  Any processes like opening and deleting emails, screen refresh, 
opening or closing files is very slow and the hard drive is working 
overtime with every mouse click or key press.
CPUs are running at 20-50%, memory runs at 85%, temp directory is 
running overtime.

Whereas performing the same in ubuntu 14.04, 386 memory runs around 35%, 
cpu's 20-50%, no hard drive temp used at all, and emails open and delete 
immediately.

I have cleaned repositories, removed unused files and software in both 
setups, run sudo yum autoclean, sudo yum clean packages. top shows 
nothing untoward.

I am running 3.15.4-200.fc20.x86_64 for this email and the system seems 
to be better but the hard drive works overtime with each change.
  kernel-3.14.8-200.fc20.x86_6 produces inode errors and boot fails.

There is a command to rebuild grub boot but I don't remember the 
details, can someone please point me to how this should be done.
What should I look for as to why the system is not operating as before.
Help much appreciated
thanks
Roger