Bottleneck and optimization of multi-image display on the same web page in IE

From: http://blog.s135.com/post/332/

The Internet Explorer browser can only download two files from the same domain name at the same time.

For the reason, see msdn blogs: Internet Explorer and connection limits. For how to lift the restrictions, see the Help and Support homepage of Microsoft customers: how to configure Internet Explorer to allow more than two download sessions at the same time.

No matter how popular Firefox is, it is undeniable that IE is still the leading browser market. Therefore, in the system architecture, you have to consider the restrictions that IE can only download two files from the same domain name at the same time. If there are more than two files, ie will wait for the two files to be downloaded in the form of a queue, and then download the next two files. In this way, when multiple images are displayed on a page, the image download speed of IE users will be affected.

Baidu, Sina, Yahoo and other websites use the same group of image servers and use multiple second-level domain names to solve this problem.

According to the analysis of httpwatch professional 5.2.17, Baidu image search uses t1.baidu.com ~ T8.baidu.com: Eight domain names are used to display images. The blocked time consumed on the IE browser is less than 0.001 seconds, which is very fast.

Sina's image CDN also uses i0.sinaimg.cn ~ I3.sinaimg.cn: Four domain names are used to display images. The blocked time consumed on the IE browser is also 0.001 seconds. Sina uses an independent top-level domain name sinaimg.cn instead of *** .sina.com.cn as the image server domain name. Another benefit is that the cookie information in the sina.com.cn domain will not be taken to the sinaimg.cn domain, this improves the speed for the image server to parse the header.

Looking at a group of image servers in NetEase album, we only use pics.photo.163.com for one domain name. The blocked time consumed on the IE browser is 0.647 seconds, which is slower.