Added Wordfence security plugin- Website Slow!

[ Moderator note: moved to Fixing WordPress. ]

I own the travel blog www.allabouttravelling.com and I noticed a few weeks ago when I went to my site, porn spam was appearing right away. I decided to use the Wordfence Security plugin to resolve this issue, and I noticed ever since adding this plugin my website has been running very slow. It only shows the first two posts, and then after a few minutes the rest of the blog posts appear.

I tried updating my plugins, checking image sizes, deleting any unused plugins.. still not sure what the issue is.

I do not know if this is a plugin issue, or some other wordpress issue.

Any suggestions would be really helpful! thanks:)