On the SMF forums someone linked to an article saying that $('<div>') was slower than document.createElement('div'). Decided to benchmark it.
Method 1: $('<div>')
Method 2: $('<div></div>')
Method 3: $('<div />')
Method 4: document.createElement('div')
Method 5: $(document.createElement('div'))
The difference between #4 and #5 is that #5 creates a jQuery object like #1-#3 while #4 doesn't. So it is a "more equal" test.
Results for 10,000 iterations:
#1: 61 ms
#2: 51 ms
#3: 34 ms
#4: 10 ms
#5: 14 ms
Recommendation: Seriously, we are talking about 47 ms for 10,000 iterations. You are liable to hit a CPU or network lag spike that lasts that long.
That said, no reason not to use $('<div />') over $('<div>')