The mantra I'm always told around slices is "Don't keep pointer slices. Don't keep pointer slices." Because the entire thing will fail escape analysis and go on

The mantra I'm always told around slices is "Don't keep pointer slices. Don't keep pointer slices." Because the entire thing will fail escape analysis and go onto the heap. But it's OK in this case, right? Because, as you say, the BigCache (including the []*cacheShard) is allocated once; never gets GC'd; and it's around forever.