Halcyon manipulates your code (Go, JS, PHP) and makes changes in order to minimize its "physical" size as well as remove unused parts. There are 2 passes during this process: The first pass will look at code that exists in all pageviews and try to identify code used only locally and removes imports when not used. The Second Pass will identify any changes in your code required by specific pageviews and split them to separate includes so that they are not loaded when not needed.

During live rewrite Halcyon checks your code and makes changes required to either use faster algorithms or target specific web clients. With this process we will combine all safe to combine CSS and JS files to one, deduplicate functionality and use code compression to reduce their size.

Usually the developer has to minify their files (CSS, HTML, JS, SVG) before uploading and in some cases this is a futile excercise in case of 3rd party libraries or applications (CRM, ERP etc) since they will revert on each update. In order to avoid this we will minify any files we detect in your account and serve the minified version.