My organization recently bought many 128GB SSDs as we start to migrate off of HDDs. They are getting pretty cheap now. A user will feel much more speed using an SSD than upgrading the processor in most cases as storage is usually the bottleneck. Well I came across the same issue on every drive I tried to migrate to. Most users are using 500GB/320GB HDDs. I did some research and as was able so solve the issue. The solution is to defrag the drive so all files are placed at the beginning of the drive, which defrag will try to do, and the goal is to shrink the drive after doing so with Disk Management. Disk Management will let you know how far the drive can be shortened, this will also be R-Drive's limit. The first thing you want to do is delete everything you don't need, and run a disk cleanup making sure to clean the system files as well when doing so. After that do the following:
1 - Run CMD as Admin and run the command "powercfg /h off". This will get rid of the "hiberfil.sys" file under the root of C:.
2 - Turn System Protection Off, this will delete all System Restore Points.
3 - Disable the Paging File, this will remove the "pagefile.sys" and "swapfile.sys" files under the root of C:.
^The reason to do those three steps is to remove the protected files that take up a lot of space that can't be defragged.
At this point I do a restart and for the heck of it run a check disk, as our next step is to defrag and we want to make sure our file system is in-tact.
When the PC comes up I use Defraggler to defrag as I can get a visual of what is going on. After it finishes, I do a restart and defrag one more time. Then in Disk Management I shrink the disk to a size below the target drive. Disk Management is the safe way to do this. Once it's shrunk I create a data image and restore to the SSD. Then after that's done I enable the things that were turned off. It's has worked every time thus far.