Changes

[https://bugzilla.mozilla.org/show_bug.cgi?id=1307504 Race Cache with Network]: When we detect that disk IO may be slow, we send a network request in parallel, and we use the first response that comes back. For users with slow spinning disks and a low latency network, the result would be faster loads. (Firefox 59)

[https://mikeconley.ca/blog/2018/01/11/making-tab-switching-faster-in-firefox-with-tab-warming/ Tab Warming]: "Tab warming" is what we're calling the process of pre-emptively rendering the layers for a tab, and preemptively uploading them to the compositor, when we're pretty sure you're likely to switch to that tab (61)