The disclosed computer-implemented method for efficient placement of virtual machines may include (1) allocating space in a cache shared by a group of virtual machines to add a new virtual machine, (2) receiving data requests from the new virtual machine for the cache, (3) recording each of the data requests as a cache hit or a cache miss in a list based on availability of the data in the cache, (4) determining a ratio of cache hits to cache misses for the new virtual machine based on the recorded data requests, and (5) placing the new virtual machine in the group of virtual machines when the ratio of cache hits to cache misses exceeds a threshold, such that the data backup device efficiently utilizes the cache for servicing the data requests from the new virtual machine. Various other methods, systems, and computer-readable media are also disclosed.