tuesday:
I have the answer for you (and your mom).
Go back in this thread and copy and print out my reply 3.
Save it as a bookmark, you will need the links, too.
Reply 3:
#3
(click above link)
IGNORE the following paragraph:
Get one of these:
(how much space is consumed on your current internal drive?)
Pay attention to all the rest.
Your mom has used almost NO space at all on that slow 1tb drive.
We need a faster USB3 EXTERNAL drive -- an "SSD".
But it doesn't need to be too large.
I suggest one of these (2.5" sata SSD, 512gb):
Ever wonder why your phone responds faster than your computer? It's because your phone runs on flash memory. Add flash to your laptop or desktop computer with the Crucial BX500 SSD, the easiest way to get all the speed of a new computer without the price. Accelerate everything.
www.amazon.com
Actually, you could probably get away with a 256gb drive... easily.
You need a USB3.1 gen2 enclosure in which to put it:
ORICO 2.5'' USB C External Hard Drive Enclosure, SATA 3.0 to USB 3.1 Gen2 6Gbps Case for 2.5 Inch HDD/SSD Support Max 6TB with UASP Tool Free(2189C3)
www.amazon.com
The drive just snaps into the enclosure, ANYONE can do this (this means YOU).
Now -- again -- follow the instructions in post 3 of this thread.
You need to first erase the drive in disk utility, and then
Download SuperDuper and use it to "clone" the contents of the internal drive to the SSD.
And then, set it to be the "new boot drive".
You and your mom will be AMAZED at the speed difference you get from this.
ONE THING:
You didn't tell us WHICH VERSION OF THE OS is currently running on the mom's iMac.
If it's High Sierra or earlier, you need to format the SSD to HFS+ (Mac OS extended, journaling enabled, GUID partition format)
If it's Mojave or later, format the drive to APFS, GUID partition format.
Good luck.