I don't know the equivalent programs on Windoze machines, unless it is your Task Manager, but you should have a service program like TOP or HTOP which shows all the running programs, with the ability to kill those which did not close properly.
Sometimes if you open a browser and close it again, it will close it's orphaned clones.
When I open a single instance of a web browser, HTOP may show four to eight or more of the browser running. These are often the active extensions which opened along with the program. In some cases, poorly written extensions may not always shut down properly when the web browser is closed. Or they may be running background tasks before closing.
It should also show you who opened the program, whether it was the user or the system. If you have closed Google Chrome and still see clones of it with your user name, they probably didn't close properly, and it would be safe to kill them.
On the rogue IE's you see running, make sure they have your user name and not the system running them, IE is integral to the Mickey$oft Windoze operating system now. Killing IE opened by the system, may crash your system. A reboot will restore it though.
If you are doing nothing on your computer, other than looking at HTOP, it should be the only program shown as running. Others are running, you may have 85 to 100 programs running, but they are not actually running, not using up % of your CPU, but waiting ready in cache, using up some of your RAM memory. Normally, after your computer has been booted up for a long time and you've done many operations, about 2/3 of your memory is consumed by cache and 1/3 waiting for the user to use.
Windoze computers are inherently slow beasts to start with, and continually get slower over time. It has been too long now since I've used a Windoze machine to know what to tell you to do to speed it back up again. Personally, back when I used Windoze to play games, about once a month I would reinstall the OS to a clean formatted hard drive to get rid of all the garbage and the bloated registry files. But then too, I always kept Dealer Install copies of the OS which contain NONE of the garbage the OEM supplied disks contain. Yogi has a better way by using a Virtual Machine to hold the OS, so it's just a matter of saving a clean copy and reloading it. Much faster than doing a new install.
I hope Yogi tells you what to do, because I honestly don't know anymore.