No matter how much you use settings or code to shrink images, they are still the same file size when served up and rendered. If you want to reduce the file size you have to scale down the image using a photo editing program, then upload the smaller image to the server to overwrite.
Second image shown here is an example.
The last image shown at the same link, it appears you are using a 3rd party to host an image to use as a favicon? Anyway, it's 8kb when normal favicons are way less. And it's unusual to use a 3rd party dependency to serve it. Can slow your site down if that 3rd party is slow.
Neither issue has anything to do with your problem however. They are just little things you can fix to reduce your kb load.
It's kind of unusual today to see a site that isn't https, as well.
I tested your site at WebPageTest and got an excellent report. I tested it several times from several different locations, devices and browsers. Different connection methods. None of the test sites experienced delays in loading your site and it graded out excellent each time. May I suggest that if the slowdowns are random and seem to be coming and going, it might have something to do with heavy traffic in the internet at large due to millions possibly billions more people using it due to the Covid outbreak.
You might contact our mutual buddy
@MySiteGuy Ken and see what he thinks about it.