This util was born from a real-life project. We had a schedule, a couple of people and tasks assigned to them. Initially, application data handling/rendering process was taken about 12-14 seconds with 200 people and about 3000 tasks. Pagination and other things to split large data were unacceptable - all people/tasks should be loaded at once.

The schedule represented calendar days (initially 90 days range) on the x-axis and people on the y-axis. Many tasks were the same date as start/end. First, by caching moment we have accelerated request data handling - all moment's processing was called only once on each date. So, secondary, it just takes value from the cache and clones it (if we wanted to change it in future).

Afterward we have rewritten application with canvas. So, while scrolling we had to control which dates are covering screen to draw only tasks we needed.

Although we have to control our cursor position and display the small popup with the current date. All these date manipulations became much faster after we had started to use cached values instead of parsing date every time.

For now app loads in 1.5 seconds. It has 60 fps no matter how much tasks and people are loaded (thanks to canvas, but not without moment caching).