webdash: optimize task list

[buchanae]

closes #547

[buchanae]

Also, closes #384 ...maybe

I added code to cache tasks in the browser, use the minimal view where possible, and stop the refresh loop when the page/tab is in the background.

It's still not ideal, but it's a substantial improvement. Previously, our task list was requesting about 500-800MB every two seconds, even when you weren't looking. Now, it's about 500 bytes when nothing has changed and nothing is running.

The page load is still slow on the first load (although faster than before). This might be improved in a number of ways: partial list rendering, server-side rendering, etc.

Our task views are kinda clunky. The basic view can still be pretty heavy, and the list doesn't need most of that weight (~500-700KB). We could improve this substantially by having server-side support for requesting specific fields, and/or being able to subscribe to an event stream.

[adamstruck]

This looks like a great improvement. Could you apply the stoping of the background refresh loop while the page is in the background behavior to the task, node list and node pages as well?

[buchanae]

Could you apply the stoping of the background refresh loop while the page is in the background behavior to the task, node list and node pages as well?

Done