[TippeX]

could be driver related.. eg: physx used (unsure if it is or not to be honest), or something similar, where the driver sees multiple cores, but the process doesn't so there is a minor bottleneck there in the transfer.. that could cause a lag

have the developers or anyone on the official forums even acknowledged that this issue exists? (if so, then i would expect they're working on it)

sounds like a tricky one to solve.. can you scan the exe and report what protection it has (if any)? as that might also help a bit..