I don’t know if you have tried this, but I ran you site through a speed testing tool (webpagetest.org)
It is free. You enter your URL, select a test location, and a connection (cable, DSL, etc.) and it will run a test and give you considerably detailed results. I will warn you that you can get Queue for a while waiting for your test to complete.
As you can see here is the result summary from you home page:
The first “F” is telling you to use gzip for compression on transfer(host would need to support this).
The ‘x’ on the end is for CDN( cloud flare maybe).
You can also click on the Details tab and get a file by file break down.
There is quite a lot, but thought it might be worth looking at since you getting a wide result you can test from different locations and speed and browsers.