Performance degraded after shrinking I was cleaning up database (SQL Server 2012 SE) by deleting old data and truncating some unnecessary tables. After deleting and truncating data performance improved and had 67% free spaces out of 16 GB database. Then run following command to shrink database with 10% free space.

DBCC SHRINKDATABASE (databasename, 10);
GO


After that database reduced to 7GB but having performance problem, see that attach screenshot. By the way, I also rebuild indexes but no luck. Getting low application performance index (Apdex) alert from New Relic app monitoring tool.



Look at the DMV query results, at least tweenty queries taking more then 1000ms! I had only 2 queries that exceed 1000ms limit.
edit:
Will delete this shortly or update based on answer to question. Realized OP mentioned he DID rebuild indexes already.  

Shrinking a SQL Server database causes the data to get massively fragmented due to how the algorithm works.  You'll want to usually presize so you don't have to shrink but don't have to worry about growths too much either.  Always easier to grow a live DB with IFI than to shrink and reindex.

Paul Randal has a great post about this in depth here.  You will want to reindex and check your fragmentation prior and after using this script ripped off here:

SELECT dbschemas.[name] as 'Schema', 
dbtables.[name] as 'Table', 
dbindexes.[name] as 'Index',
indexstats.alloc_unit_type_desc,
indexstats.avg_fragmentation_in_percent,
indexstats.page_count
FROM sys.dm_db_index_physical_stats (DB_ID(), NULL, NULL, NULL, NULL) AS indexstats
INNER JOIN sys.tables dbtables on dbtables.[object_id] = indexstats.[object_id]
INNER JOIN sys.schemas dbschemas on dbtables.[schema_id] = dbschemas.[schema_id]
INNER JOIN sys.indexes AS dbindexes ON dbindexes.[object_id] = indexstats.[object_id]
AND indexstats.index_id = dbindexes.index_id
WHERE indexstats.database_id = DB_ID()
ORDER BY indexstats.avg_fragmentation_in_percent desc