Google Inbox initially did not support Firefox because "Firefox was too slow" [1]. Inbox hit a performance problem with Firefox's Array slice() implementation,

Google Inbox initially did not support Firefox because "Firefox was too slow" [1]. Inbox hit a performance problem with Firefox's Array slice() implementation, but Google didn't report the problem to Mozilla. Chrome's slice() was fast, in part because it was not handling some corner cases correctly. Once Mozilla engineers were made aware of the performance problem, they fixed it in one day [2]. [1] https://news.ycombinator.com/item?id=8495498 https://news.ycombinator.com/item?id=8495498 [2] https://bugzilla.mozilla.org/show_bug.cgi?id=1087963 https://bugzilla.mozilla.org/show_bug.cgi?id=1087963