Update statistics on sys.objects
The warnings you're seeing most likely come from the sys.sysdepends view.

If you script it out using 

EXEC sys.sp_helptext @objname = N'sys.sysdepends'


The definition has a bunch of converts and other nonsense going on.

CREATE VIEW sys.sysdepends AS  
 SELECT  
  id = object_id,  
  depid = referenced_major_id,  
  number = convert(smallint,  
   case when objectproperty(object_id, 'isprocedure') = 1 then 1 else column_id end),  
  depnumber = convert(smallint, referenced_minor_id),  
  status = convert(smallint, is_select_all * 2 + is_updated * 4 + is_selected * 8),  
  deptype = class,  
  depdbid = convert(smallint, 0),  
  depsiteid = convert(smallint, 0),  
  selall = is_select_all,  
  resultobj = is_updated,  
  readobj = is_selected  
 FROM sys.sql_dependencies  
 WHERE class &lt; 2  
 UNION ALL  
 SELECT  -- blobtype dependencies  
  id = object_id, depid = object_id,  
  number = convert(smallint, column_id), depnumber = convert(smallint, type_column_id),  
  status = convert(smallint, 0), deptype = sysconv(tinyint, 1),  
  depdbid = convert(smallint, 0), depsiteid = convert(smallint, 0),  
  selall = sysconv(bit, 0), resultobj = sysconv(bit, 0), readobj = sysconv(bit, 0)  
 FROM sys.fulltext_index_columns  
 WHERE type_column_id IS NOT NULL  


sys.objects, on the other hand, is fairly straightforward.

CREATE VIEW sys.objects AS  
 SELECT name,   
  object_id,  
  principal_id,  
  schema_id,  
  parent_object_id,  
  type,   
  type_desc,   
  create_date,   
  modify_date,  
  is_ms_shipped,  
  is_published,  
  is_schema_published  
 FROM sys.objects$  


The view definition for sys.sysdepends causes the same warnings when queried on its own.

SELECT *
FROM  sys.sysdepends  


In general, if you want to control datatypes and indexes and have some performance tuning ability when referencing system views or tables, your best bet is to dump them into a temp table first.