A web application firewall (WAF) is an application firewall for HTTP applications. It applies a set of rules to an HTTP conversation. Generally, these rules cover common attacks such as Cross-Site Scripting (XSS) and SQL Injection.
So from what I understand, this will handle only HTTP. What will happen if HTTPS traffic goes through the WAF?
Does it reduce the request time? or are there any performance issues?
...is an application firewall for HTTP applications
can be confusing. In my opinion it would have been better to use the term web applications and leave the protocol out of it.