To fix slow IO performance with Vagrant and VirtualBox, start by reading the documentation:
It’s a long known issue that VirtualBox shared folder performance degrades quickly as the number of files in the shared folder increases. As a project reaches 1000+ files, doing simple things like running unit tests or even just running an app server can be many orders of magnitude slower than on a native filesystem (e.g. from 5 seconds to over 5 minutes).
If you’re seeing this sort of performance drop-off in your shared folders, NFS shared folders can offer a solution. Vagrant will orchestrate the configuration of the NFS server on the host and will mount of the folder on the guest for you.
Example NFS configuration:
```
Vagrant::Config.run do |config|
config.vm.share_folder("v-root", "/vagrant", ".", :nfs => true)
end
```
After this run:
```
vagrant reload
```
On OSX you can check that the folder is mounted properly with:
```
showmount -e
```
Or check /etc/exports
On Linux use:
```
sudo mount
```
Or check /etc/fstab