How many tasks are currently waiting?

select
count(*)
from
sys.dm_os_waiting_tasks

This query will give you an idea of how many tasks are waiting in the system. You can use this information to understand blocking characteristics of your load

How many sockets does my machine have in SQL Server?

select
cpu_count/hyperthread_ratio AS sockets
from
sys.dm_os_sys_info

Buffer Cache Hit Ratio

Buffer Cache Hit Ratio shows how SQL Server utilizes buffer cache
“Percent of page requests satisfied by data pages from the buffer pool”

SELECT object_name, counter_name, cntr_value
FROM sys.dm_os_performance_counters
WHERE [object_name] LIKE '%Buffer Manager%'
AND [counter_name] = 'Buffer cache hit ratio'

The recommended value for Buffer Cache Hit Ratio is over 90. A lower value indicates a memory problem.