It looks like memory is consumed by Windows file cache. It releases memory, when file is closed. Unfortunately, it's size can't be controlled from application. We are working on finding some other way to solve the problem with 4k block disk.
Our developers report that they created a fix for this issue, currently it marked as submitted to our Q&A I think the ETA for the fix is approximately 2-3 weeks. We'll update the post as soon as a fix is available for public download.