Help needed for webprog24

Hello,

I run the website https://www.webprog24.com and I am beginning to bang the head against the wall because the page speed is low. I did really a lot:

[list]
[]Varnish
[
]Memchached
[]APC Cache
[
]Cloudflare
[]Compression of JS and CSS
[
]whatever
[/list]

The problem is the website is dramatically slow. It just does not work the way I want. I have a few small things I can do but in general, I really did a lot to increase the page speed of this website. Can anybody give me tips on how to improve the page speed there?