Slow running - multiple openings

My Avast Browser has become incredibly slow to load and browse.
By accident I have just noticed that despite having only one window open for Avast Browser, Task Manager is showing Avast has opened itself 16 times!
I don’t know if this is the cause of slow running, but if it is, what do I do to get things back to how they should be?

Going through this as well. Each opening is an extension. Reduce the extensions.
Outside of this, the browser is really slow even with all the extensions off.