Citrix ADC Front-End Optimization (FEO) offers Image Optimization, which automatically re-encodes and compresses GIF, PNG and JPEG files, eliminates unnecessary color tables or meta-data, and can convert GIFs to more efficient formats. Smaller optimized images traverse the network and render in the browser faster, eliminating the end-user delay observed while GIFs appear during scrolling, thereby accelerating overall page load time.

A. Domain sharding only spreads object requests across multiple host names to increase TCP connections; it does not reduce the size or render time of individual GIFs.

B. Image lazy loading defers downloading images that are below the fold; it does not accelerate the rendering speed of GIF files once they are requested.

D. Image shrink-to attributes resizes images based on HTML width/height attributes; it mainly helps oversized photographs, not the compression or encoding issues of standard-sized GIFs.

1. Citrix ADC 13.1 Front-End Optimization Guide – “Image Optimization

” pp. 8-10; explains GIF re-encoding and compression to improve load time.

2. Citrix ADC 13.1 Product Documentation – “FEO Transformations

” Table 1

column “Benefit

” states image optimization “reduces image size; faster browser rendering.”

3. Citrix Systems

Inc. Tech Brief “Accelerating Web Applications with Citrix ADC FEO

” section 2.2

para 3: details GIF → PNG conversion and impact on perceived performance.

4. MIT OpenCourseWare 6.033 “Web Performance” lecture notes

p. 5: confirms that reducing object size (compression/re-encoding) is the primary method to speed image rendering.