Grant Fritchey (5/7/2014)
Not sure about the encryption. I'm not sure why that would affect performance much at all (a little in the CPU I suppose).
As to figuring out how the server is running, there are a ton of tools built into SQL Server. First, and most important, are the dynamic management views (DMV). The very first one of those you'd start with to understand why or how a system is running slow is sys.dm_os_wait_stats. That will show you what the server is waiting on. You can also use the DMVs to look at currently existing queries (sys.dm_exec_requests) an aggregation of query performance for queries in cache (sys.dm_exec_query_stats) and others. There's a book on this (free download e-book) by Tim Ford and Louis Davidson.
Another tool is to run perfmon to capture performance monitor metrics. This will let you capture general behavior and load indicators such as cpu percentage, memory use, and others.
After that, you start to get into more specialized tools such as extended events to capture certain types of behavior or events such as query execution time and other things.
There's a lot to this. In fact, the first several pages of my book (in the signature below) are all about capturing system behaviors in order to understand where your system is running slow.
The query below returns the results as you see here:
select top 10 *
order by wait_time_ms desc
Where do I start looking into the main delays which seem to be the first two here . i.e.:
DBMIRROR_EVENTS_QUEUE and DBMIRRORING_CMD
wait_type waiting_tasks_count wait_time_ms max_wait_time_ms signal_wait_time_ms
DBMIRROR_EVENTS_QUEUE 12338274 4097232094 3009 1769603
DBMIRRORING_CMD 2263712 4032912239 86412339 449678
BROKER_TASK_STOP 14885480 1412496074 10015 1517342
CLR_AUTO_EVENT 55 1256037956 132505908 65
REQUEST_FOR_DEADLOCK_SEARCH 136785 683935830 5170 683935830
LAZYWRITER_SLEEP 696243 683929387 1829 126417
XE_TIMER_EVENT 22799 683915038 30175 683913037
XE_DISPATCHER_WAIT 1523 683914454 246810002 0
LOGMGR_QUEUE 1393192 683814529 34100 218580
SQLTRACE_INCREMENTAL_FLUSH_SLEEP 170566 682280600 4181 1