Deleting characters in a textarea on an HTML page with more than a few thousand characters is incredibly slow on an iPhone X device.<p>STEPS:
1. Visit <a href="https://missiveapp.com/iphone_x_test_case" rel="nofollow">https://missiveapp.com/iphone_x_test_case</a> with an iPhone X
2. Focus the textarea
3. Touch the backspace key to delete characters<p>Boom! The iPhone X UI will hang for a few <i>seconds</i>! every time the word suggestion bubble appears.<p>This slowness only affects iPhone X, other models will delete characters with no sluggishness.<p>I post this here to raise awareness at Apple... it has been the case for the last 6 months.