The number one reason that small sites like this have performance issues is because of disk IO. If this is a virtual machine, ensure that you are following the vendor recommendations for virtualizing SQL (don’t over commit processors/cores, ensure SQL data files, tempdb, and logs are on separate spindles, format SQL drives with 64KB block sizes, split SQL data files).
CPU does not matter too much. Disk i/o is more important. Also see http://technet.microsoft.com/en-us/library/hh846235.aspx#BKMK_ReqRemoteSiteSystems
MP replica might take some load off of an MP, but it also adds extra load because of SQL replication.
Content transfer can be scripted: http://technet.microsoft.com/en-us/library/jj821831(v=sc.20).aspx(in case you did not use a DP group).
Are you experiencing current perf issues with all roles on the site server itself? Can you describe these perf issues?
Have you setup a DB re-indexing and statistics rebuild agent task?
Have you run perfmon to baseline the perf of the system?
Is the system a VM on an over-committed host and/.or is it sharing spindles with other applications?