Internet Explorer 11 problem

My wife insists on using internet explorer, but her laptop has started to have a problem with it.
When she turns on the computer and opens IE, everything works fine, but after browsing for a while, the browser either locks up or becomes very slow.
when I go into task manager and go to the processes tab, I will find 3 or 4 instances of internet explorer running. If I stop them all and reopen the browser, it works fine, but the same thing happens over and over again.
using IE 11 and Windows 7.
Does anyone have any thoughts on what could be causing this?
I keep telling her to just use Firefox which is already installed, but she is reluctant to do so.
Thanks
Answer #1
I would guess that each instance of IE would be the amount of tabs open
Ergo, more tabs, more instances, slower performance (just a guess again) Also, remove any toolbars that may be present in IE
Answer #2
Dialogue boxes?
http://www.pcworld.com/article/2466140/internet-explorer-running-slow-dialog-boxes-could-be-at-fault.html
Other stuff..
http://answers.microsoft.com/en-us/ie/forum/ie10-windows_7/internet-explorer-is-extremely-slow-on-windows-7/9811e1ae-c994-4eaf-a2d1-05017ae6eefb
Answer #3
Whenever I have trouble convincing people to switch from IE (especially when their computer runs slow). I always install and run a scan with the free malwarebytes. Usually it’ll hit on the hundreds of malware/spyware/adware that IE has let go through. Which is more than enough evidence to convince them to switch to another browser. Plus, you can then remove the malware, get them on a safe browser, computer runs better. Everyone is happy!
Answer #4
O.K. I cold booted the laptop opened IE, left it open, immediately went to task manager and there are already 3 instances of iexplore.exe
Just a thought, I have Internet download manager installed. Could that have something to do with it?
IE 11 was not installed as an upgrade, I did a completely fresh install and and ran windows update once.