Hi Walshy, thank you for reporting this.
It is expected that the Win64 Client will consume more memory than the 32-bit one due to some innate differences (64-bit pointers being twice as large as 32-bit ones, struct alignment, etc…). On top of that, there might be some additional memory overhead due to Hyperion as well.
We are monitoring the situation and OOM crash counts in particular. So far everything is within expected parameters, but if we see problems we should be able to take some corrective actions on our side. In the meantime, if you feel like this is affecting your users, please feel free to post Client logs or crash dumps here so that we can investigage.
Thanks!
-ScipioAfrikanos