With 25 tabs open in google chrome,itunes, MS Word & Quicktime all open (not playing) , is it worth upgrading iMac RAM from 8GB? will wifi speed improve?

Are you using your phone as your internet connection?

FWIW, RAM has nothing to do with connection speeds.

And, having tabs open will use wifi since open apps will continuously and automatically update their content of their website, so they connect. Try it with only one or two tabs open.

The new metrics for Mac RAM performance are Memory Pressure and Swaps, not "Used." This changed at about MacOS 10.10 (±). At the time you did the screenshot your RAM was not being stressed. Your pressure was in the green and your swaps (one MB) would not even report were they any less.

However, Chrome is a known resource hog and you have it in the User Login Items so it running all the time. As you've already noted, its minion "helpers' are the ones that eat resources. If you MUST use Chrome, remove it from User Login Items. Better to launch it when you need it and close it when done.

I suggest you use the program created by Etresoft, a frequent contributor.  It will provide a snapshot of your system which we can analyze to possibly determine the cause of your problem. Please use copy and paste as screen shots can be hard to read. On the screen with Options, please open Options and check the bottom 2 boxes before running. Click “Share Report” button in the toolbar, select “Copy to Clipboard” and then paste into a reply.

https://itunes.apple.com/us/app/etrecheck/id1423715984?mt=12

Use the Add Text button to include the Etrecheck report in your reply:

Thank you,

Your 4MB at the socket is already at the bottom performance. (very low)

You might improve it using a cable connection to you iMac.

You might significantly improve it using your iPhone with Internet Plan and then share the internet with your iMac.

Look it up, and compare to what you pay now for the bad service.

Also here is where you can look up for best boradband in your area https://www.broadbandchoices.co.uk/broadband/best-deals

Run a Speed test http://www.speedtest.net/

Conect your iPhone to the WiFi and look what it gets to compare to your iMac.

Scan the WiFi neighborhood to see how crowded it is, since you live in a appartment it can be very crowded and that might slowdown your WiFi speed.

Change the WiFi chanel on your Router to less crowded one.

If you have a modem/router, why can you not test it with using an ethernet cable?

And, what is the connection speed plan you have signed up for?

As for RAM, visit OWC.

https://eshop.macsales.com/shop/memory/iMac/Retina-5K2015/DDR3L

They also have excellent install videos.

Ethernet cables aren’t expensive and available widely. You canimprove your speed with that. I am guessing you have DSL?

You can read about the wifi capabilities of your router here

https://www.broadbandchoices.co.uk/guides/hardware/plusnet-hub-zero

Based on that, I’d find an ethernet cable.

The RAM specs look ok.

Babowa and I didn't think your internet speed had much to do with your internet speed. As far as running " optimally", your memory pressure is low as it should be.

If I understand you right all you are interested in is to speed up your Internet.

What hardware do you have between your Phone socket and you iMac ?

Please be specific with like Modem/Router Name.Model ect.. so we can look up how to help you.

Do you have any other device on Internet?

Did you happen to test your connection speed with less tabs and apps open at one time? Also, are you using Wifi or Ethernet? Wifi is always slower.

When you look at Activity Monitor under the Memory tab, how much Ram are all the Google Chrome processes taking?

The new OS versions are coded to use all/whatever amount of RAM they need; someone decided that unused RAM is wasted RAM, so let's use it all. As well, newer OS versions demand more RAM to run well.