See attached screencast which compares Chrome to Epiphany to Firefox. As shown there, we don't seem to ever truncate the title that's shown in the tab-title; whereas Chrome truncates at 4096 characters, and epiphany truncates-with-an-added-ellipsis at 512 characters.
Bug 736194 Comment 5 Edit History
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See attached screencast which compares Chrome to Epiphany to Firefox. As shown in the screencast: Chrome truncates at 4096 characters, and epiphany truncates-with-an-added-ellipsis at 512 characters, whereas Firefox doesn't seem to ever truncate the title that's shown in the tab-title (which is why this can end up causing a hang or a crash in the parent process).