FlashPlayer plugin stay in memory

It is most likely ad-ware something, the flashplayer plugin kept in memory even after webpage is closed.
The bad thing is they take up memory, what's more harmful, they keep accessing the internet, keeping downloading and uploading something sneaky. If you find your CPU usage high, they are maybe using your CPU for mining coins! The worst case is using unknown vulnerability to reading your local files!

I like to use Firefox for browsing, a pity, the problem occur on both Windows and Freebsd, likely on Linux.
On windows, there are 1 or 2 process named something like flashplayerplugin, you can kill them in task-manager. Most time they will quit when Firefox is closed.
On Freebsd or Linux, they stay as processes even after Firefox is closed.
eg, I viewed some p0rn sites and after that, I found 300+ processes of flashplayerplugin! wtf...

so there is a shell script to kill them all, like this:

#!/bin/sh
ps auxw | awk '/[\/]libflashplayer/{print $0}'
cnt=`ps auxw | awk '/[\/]libflashplayer/{print $2}' | wc -l`
echo $cnt
if [ $cnt != 0 ]
then
    kill `ps auxw | awk '/[\/]libflashplayer/{print $2}'`
    sleep 1
fi
ps auxw | awk '/[\/]libflashplayer/{print $2}' | wc -l

I really hate swf things, swf can access various sites at once as ad-ware.
but we have to use them watching video before they are replaced by HTML5 video. They also silently embedded in the webpages of some evil sites, even technical sites like solidot.org. Fuck them all.
Just keep a sight on them.