Well I'd guess you went up from 5400rpm to 7200rpm and the former is no contender with the latter all other things being equal (and I presume they're not given how fast HD tech moves, so the old disk wouldn't've been a contender anyways). A possibility is that your OS swaps parts of RAM to HD when playing EB, something which should've gained a massive boost simply from improved sequential read times, however... that begs the question why you'd get away with 1:15 previously... (swapping trashes performance, due to the fact that a HD is easily a factor of 1000 slower than any RAM).
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