We have an iMac 27 inch Retina 2019. Sometimes it gets slow.

It only has the 8Gbytes of main memory it came with - checked in About This Mac.

My understanding is that the Crucial upgrades should work with this model.

Looks like there are 4 slots, so to take it up to 32 Gbytes would presumably have to take out an 8Gbyte module, and put 4 x 8 Gbyte modules in.

I could source these from Crucial for about £120.

My gut feeling is that if I can do this, that would make a significant difference to the performance of the machine.

I could also buy yet another offline storage device, and back up a lot of the files on the SSD which are cluttering it up, though I don't know how significant that would be in terms of speed up.

I think one or two people round here have done this kind of upgrade on a similar iMac.

Even though the M1 iMacs may be faster, I don't think I can reasonabaly buy yet another computer - and I do like the 27 inch display of this one