For five runs, on the same hardware with the same load:
+ Unclosed: 4.00s, 3.91s, 3.59s, 4.45s, 3.93s
+ Closed: 3.90s, 2.74s, 3.9s, 2.05s, 3.39s
Though I'd note that the newline you have immediately following the paragraph, even when closing, would probably reduce the backtracking effect. And having no explicit body or head element would probably cause some different rendering patterns as well.
+ Unclosed: 4.00s, 3.91s, 3.59s, 4.45s, 3.93s
+ Closed: 3.90s, 2.74s, 3.9s, 2.05s, 3.39s
Though I'd note that the newline you have immediately following the paragraph, even when closing, would probably reduce the backtracking effect. And having no explicit body or head element would probably cause some different rendering patterns as well.