I tried virtualbox+linuxmint under windows64 on zillioncoin (similar to zettelkasten spredcoin-cpuonly-fork) On native linux (liveusb) it has 30 kh/s, on virtualbox 28kh/s, on windows 32bit-wallet it has 15 kh/s. So i think, this is allowable alternative. Slowdown is about 10 percents vs 50 on win32 wallet.