Maybe you just have a cheap and slow company to host your blogs. Then find a better one.
But there might be other things you can do. I leave it to you to work through the tips google found in https://www.google.com/search?&q=increase+website+loading+speed+for+wordpress
We can't see what would be most effective. You can try.
I have created around 10-12 blog and every blog has been approved by google for advertisement.
my questions is - my blog is slow after more visitors or traffic.......
please tell me how to increase website loading speed for wordpress blog or website.