Best Practices for Speeding Up Your Web Site - Minimize the Number of iframes

Iframes allow an HTML document to be inserted in the parent document. It's important to understand how iframes work so they can be used effectively.

<iframe> pros:

 
• Helps with slow third-party content like badges and ads
 
• Security sandbox
 
• Download scripts in parallel

<iframe> cons:

 
• Costly even if blank
 
• Blocks page onload
 
• Non-semantic