Can you tell me your experience about RAM upgrade a little bit?

I have a 27" iMac18,3 with 16 GB of RAM. I'm able to open a 288 MB image file almost immediately:

However, opening speed of files us more depending on the speed of the hard drive than on memory. Memory helps in processing of images once they are open.

There are two late 2013 21.5" iMacs, Model ID 14,2 and 14,3. Only the 14,2 model is user upgradeable (per the donation ware app MacTracker).. If you have the model that is user upgradeable increasing the RAM to 16 would definitely help with processing large image files.

If you have the 14,3 model and you're adept at electronics it would behove you to have an Apple Authorized Service Provider add the extra RAM. Opening that vintage iMac is not for the faint of heart. Apple won't do it and if you try yourself you'll be voiding the warranty.

However, if you have the 14,2 model you can do it yourself with RAM modules from Crucial.com or MacSales.com. Those are the only two vendors which I will recommend as they guarantee their modules will work in the model they are intended for.

Regarding an additional SSD you can add an external SSD rather inexpensively which will allow you to store your image files on and have them open very quickly as shown in the gif screenshot. I use this setup:

The SSD is from MacSales.com (OWC) and the adaptor is from Amazon.

Here's hoping you have the 14,2 model.

My ram routine is to open a photo which is large such as tiff, etc. If I get the spinning wheel or it takes too long to open then more ram is going to speed that up greatly.

Yes, as OS's increase in capabilities and Apps gain additional functionality this all uses RAM. You are correct Chrome is pretty inefficient at managing RAM especially if you like to have more tabs open. There are much more efficient browsers than Chrome, I prefer Safari but you can choose what you want.

As you know your 21.5" iMac cannot have the RAM expanded so it's to your benefit to buy a Mac with 16 GB or more of RAM. Yes having RAM definitely helps as not having enough will slow down you system because the system is forced to do RAM swapping which basically is robbing one process to support another or robbing Peter to pay Paul. In short, you can never have too much RAM.

I have a iMac (21.5-inch, Late 2009 and J am too wanting to upgrade my iMac's RAM. if its doable. Since I am fairly new with the Apple, My question is; can I upgrade the RAM to 16 GB to speed up the processors; as my wife complained that it is slow in opening a n excel spreadsheet.