This warning is not yet supported for MSSQL or remote databases.
Index Queue not empty
Can be ignored if intermittent small numbers
Contact support if large numbers persist
HTTP pool too full
in multiserver.conf increase HTTP pools like Connection.CM_0.NumThreads to at least double the number of active users. (you may also have a CM_1 if you are using HTTP and HTTPS)
DB pool full
The default setting of 30 in intranet.conf for DatabaseManager.DB.intranet.Connection.MaxPoolSize is already fairly high so normally this is an indication that the SQL server getting bogged down by slow spinning storage (LVMCache is recommended).
Increasing the number without ensuring the DB pool was filled because of volume (not latency) will likely cause out of memory or deadlock errors on the database instead of just slowness.