Yes, but you would have to drop -way- back to Yosemite or even Mavericks to see a major difference in memory usage.
I'd suggest staying with High Sierra and expediting the memory upgrade.
Apple wants you to buy a new computer.Thanks Everyone Ordering the extra memory now. Just out if curiosity what is the reason Apple says the 2011 can't Run Mojave?
Gary
Apple wants you to buy a new computer.
I still am using the same iMac as yours. But I added 4 GB RAM. It is much faster when booting up, shutting down, and opening apps.
I had added two 4GB ram cards but one turned out to be defective. So I currently have 8 GB but it is still much faster than before.
I considered SSD upgrade also but after seeing the improvement with only RAM upgrade, I won't get SSD.
if I understand correctly you have 3 memory slots occupied? You don't have to add them 2 at time?
Gary
Thanks Everyone Ordering the extra memory now. Just out if curiosity what is the reason Apple says the 2011 can't Run Mojave?
Gary
It's possible. There's a hack and a patch. I've done it. Avoid!Just out if curiosity what is the reason Apple says the 2011 can't Run Mojave?
That makes it sound like someone's arbitrary decision. It's not.The 6xxM GPUs don't support the new Metal API, which the Mojave operating system apparently now exclusively uses.
Update
Friday of this week I turned the Imac on and after 10 minutes I heard the loudest popping noise I ever heard anything make. quickly I turned it off and called the people I bought it from. They said send it back to them and they will replace it. So for now I'm back to my 2007 Mac Mini till the new unit arrives
Gary
Where did you buy the used/refurbished iMac from?
I considered SSD upgrade also but after seeing the improvement with only RAM upgrade, I won't get SSD.
Running High Sierra on SSDs in my 2010 and 2011 27” iMacs. Works great.
There is no point to APFS on an HDD. The High Sierra installer will not attempt to format it that way. If installing on an internal SSD, it will format APFS.
UPDATE.. www.macofalltrades.com Sent the replacement unit and it runs like gangbusters. no loud fan noise all excellent!!!
This is so different The imac that failed the day it arrived after 10 minutes of use the fans were running full blast and loud. The replacement even after watching an hour of video on Itunes no fan noise at all
Gary
what are yout temperatures saying .. ?
post a screenshot here from macsfancontrol program.
2011 imac's are known to get very hot AMD GPU's !!
these iddle temps. look fine to me.
post them new temp. screenshot, after watching a movie for example or doing something intensive with your mac..