Contact Form 7 seems to have a great following. It helps your site to process web forms, and turn them into emails.
The code seems fairly old, and does lots of bad things, including :
So Contact Form 7 can slow down every page, and clag out the server’s CPU – great, thanx.
I’d suggest you replace your Contact Forms 7 with something more modern.
Here are some suggestions : gravity forms, ninja forms, fast secure contact form.