Re: java8 up to 6x slower than java7

i wrote a little pathfinder. i can run it under the jdk7 update 51
and it is done in ~20 seconds. under java8, since a long series of
builds, a certain part involving deeeeeeeeeep recursion takes ~60
seconds instead of 10. i suspected the hashmap change of java8 to be
the culprit since i perform a lot of put operations, but that's not
it - i used the standard hashmap from scala to be 100% sure the
hashmap can't be the reason (or is), and indeed, i get the same
performance difference between java7 and 8 with the same hashmap my
profiler (yourkit) shows that java8 spends a much bigger amount of
time on garbage collection and allocated more objects. if i take a
memory snapshot, can see that the final results are equal, so i have
more temporary objects. yourkit also shows that more objects are
allocated using java8. what is up with that? all i do in the critical
method is creating arraylists and performing puts, contains and gets
on a hashmap, and the recursive call. the time is, according to
yourkit, spend in the method itself, not inside the hashmap or
arraylist constructor. any ideas?