SharePoint 2013 introduces a new service to cache authentication token and My Site social feeds. Only local cache hosts can be used and only the shipped caching by sharepoint  can be used, you cannot upgrade it

This caching service is to be installed on each server in the farm when SharePoint is installed. You can manage the service via “Services” on server page in Central Admin. The name of the service is “Distributed Cache service”. With that, you can actually turn on/off on this service for your servers. By default, all SharePoint servers will be running this service and to form a Cache Cluster. You may want to consider dedicating a server to serve only caching service for your environment (if you have resource to do so, 2 cents)

To setup the Cache Service, you need farm account with local admin rights. After setup is complete, you may then lower the privileges for this account.

Cache Server Performance: Few key performance counters are available for your assessment. such as:

1. # of reads
2. # of writes
3. # of hits
4. # of misses
5. time for read
6. time for write
7. Total I/O (data transferred in a given period of time)

With these indicators, you may be able to access the performance and probably to increase the number of caching servers.