At one point I had to move some VMs to a NTFS partition and forgot that the ntfs driver can cause overhead. For regular use it's not noticeable as much, but for high IO it can create high CPU load.

The mount.ntfs was creating lot of load on the CPU. There are some workarounds, for example to change options in fstab which I didn't want to touch because they are tuned for some specific application which I don't want to break. Then there are ways where VMware can cause less IO, which can cause moving files to /tmp, or to keep them in memory with mixed experiences with different people. Or just to move it to ext partition, because I didn't like any other approach I just quickly resized the NTFS and EXT partitions and moved the VMs to the ext.