system table weirdness

Question

I've got a 15Gb database and Sql Server 2014. When in visual studio I try 'update model from database' it hangs. Sql profiler showed sql that VS launched and that was very slow. The part of sql and execution plan below. In execution plan the culprit seems to be sys.sysschobjs table which takes 6% in many places (one is showed). The interesting part is that sql uses only these tables

INFORMATION_SCHEMA.TABLES
INFORMATION_SCHEMA.COLUMNS
INFORMATION_SCHEMA.VIEWS
INFORMATION_SCHEMA.TABLE_CONSTRAINTS
INFORMATION_SCHEMA.KEY_COLUMN_USAGE

all of which fairly small (largest has 1798 records), but the query itself takes 51 minutes. Any ideas on how to fix that would be appreciated.

EDIT I suspect that sys.sysschobjs indexes need to be rebuild. Should I do that taken that it's a system table?

Excerpt from sql:

exec sp_executesql N'SELECT 
[UnionAll1].[Ordinal] AS [C1], 
[Extent1].[CatalogName] AS [CatalogName], 
[Extent1].[SchemaName] AS [SchemaName], 
[Extent1].[Name] AS [Name], 
[UnionAll1].[Name] AS [C2], 
[UnionAll1].[IsNullable] AS [C3], 
[UnionAll1].[TypeName] AS [C4], 
[UnionAll1].[MaxLength] AS [C5], 
[UnionAll1].[Precision] AS [C6], 
[UnionAll1].[DateTimePrecision] AS [C7], 
[UnionAll1].[Scale] AS [C8], 
[UnionAll1].[IsIdentity] AS [C9], 
[UnionAll1].[IsStoreGenerated] AS [C10], 
CASE WHEN ([Project5].[C2] IS NULL) THEN cast(0 as bit) ELSE [Project5].[C2] END AS [C11]
FROM   (
        SELECT
        quotename(TABLE_SCHEMA) + quotename(TABLE_NAME) [Id]
        ,   TABLE_CATALOG [CatalogName]
        ,   TABLE_SCHEMA [SchemaName]
        ,   TABLE_NAME    [Name]
        FROM
        INFORMATION_SCHEMA.TABLES
        WHERE
        TABLE_TYPE = ''BASE TABLE''
      ) AS [Extent1]
INNER JOIN  (SELECT 
    [Extent2].[Id] AS [Id], 
    [Extent2].[Name] AS [Name], 
    [Extent2].[Ordinal] AS [Ordinal], 
    [Extent2].[IsNullable] AS [IsNullable], 
    [Extent2].[TypeName] AS [TypeName], 
    [Extent2].[MaxLength] AS [MaxLength], 
    [Extent2].[Precision] AS [Precision], 
    [Extent2].[DateTimePrecision] AS [DateTimePrecision], 
    [Extent2].[Scale] AS [Scale], 
    [Extent2].[IsIdentity] AS [IsIdentity], 
    [Extent2].[IsStoreGenerated] AS [IsStoreGenerated], 
    0 AS [C1], 
    [Extent2].[ParentId] AS [ParentId]
    FROM (
          SELECT
          quotename(c.TABLE_SCHEMA) + quotename(c.TABLE_NAME) + quotename(c.COLUMN_NAME) [Id]
          ,   quotename(c.TABLE_SCHEMA) + quotename(c.TABLE_NAME)                             [ParentId]
          ,   c.COLUMN_NAME   [Name]
          ,   c.ORDINAL_POSITION [Ordinal]
          ,   CAST( CASE c.IS_NULLABLE WHEN ''YES'' THEN 1 WHEN ''NO'' THEN 0 ELSE 0 END as bit) [IsNullable]
          ,   CASE
          WHEN c.DATA_TYPE in (''varchar'', ''nvarchar'', ''varbinary'') and
          c.CHARACTER_MAXIMUM_LENGTH = -1 THEN
          c.DATA_TYPE + ''(max)''
          ELSE
          c.DATA_TYPE
          END
          as [TypeName]
          ,   c.CHARACTER_MAXIMUM_LENGTH [MaxLength]
          ,   CAST(c.NUMERIC_PRECISION as integer) [Precision]
          ,   CAST(c.DATETIME_PRECISION as integer)[DateTimePrecision]
          ,   CAST(c.NUMERIC_SCALE as integer) [Scale]
          ,   c.COLLATION_CATALOG [CollationCatalog]
          ,   c.COLLATION_SCHEMA [CollationSchema]
          ,   c.COLLATION_NAME [CollationName]
          ,   c.CHARACTER_SET_CATALOG [CharacterSetCatalog]
          ,   c.CHARACTER_SET_SCHEMA [CharacterSetSchema]
          ,   c.CHARACTER_SET_NAME [CharacterSetName]
          ,   CAST(0 as bit) as [IsMultiSet]
          ,   CAST(columnproperty( object_id(quotename(c.TABLE_SCHEMA) + ''.'' + quotename(c.TABLE_NAME)), c.COLUMN_NAME, ''IsIdentity'' ) as bit) as [IsIdentity]
          ,   CAST(columnproperty( object_id(quotename(c.TABLE_SCHEMA) + ''.'' + quotename(c.TABLE_NAME)), c.COLUMN_NAME, ''IsComputed'' ) | CASE WHEN c.DATA_TYPE = ''timestamp'' THEN 1 ELSE 0 END as bit) as [IsStoreGenerated]
          , c.COLUMN_DEFAULT as [Default]
          FROM
          INFORMATION_SCHEMA.COLUMNS c
          INNER JOIN
          INFORMATION_SCHEMA.TABLES t ON
          c.TABLE_CATALOG = t.TABLE_CATALOG AND
          c.TABLE_SCHEMA = t.TABLE_SCHEMA   AND
          c.TABLE_NAME = t.TABLE_NAME       AND
          t.TABLE_TYPE = ''BASE TABLE''
      ) AS [Extent2]
UNION ALL
        SELECT 
        [Extent3].[Id] AS [Id], 
        [Extent3].[Name] AS [Name], 
        [Extent3].[Ordinal] AS [Ordinal], 
        [Extent3].[IsNullable] AS [IsNullable], 
        [Extent3].[TypeName] AS [TypeName], 
        [Extent3].[MaxLength] AS [MaxLength], 
        [Extent3].[Precision] AS [Precision], 
        [Extent3].[DateTimePrecision] AS [DateTimePrecision], 
        [Extent3].[Scale] AS [Scale], 
        [Extent3].[IsIdentity] AS [IsIdentity], 
        [Extent3].[IsStoreGenerated] AS [IsStoreGenerated], 
        6 AS [C1], 
        [Extent3].[ParentId] AS [ParentId]
        FROM (
              SELECT
              quotename(c.TABLE_SCHEMA) + quotename(c.TABLE_NAME) + quotename(c.COLUMN_NAME) [Id]
              ,   quotename(c.TABLE_SCHEMA) + quotename(c.TABLE_NAME)                             [ParentId]
              ,   c.COLUMN_NAME   [Name]
              ,   c.ORDINAL_POSITION [Ordinal]
              ,   CAST( CASE c.IS_NULLABLE WHEN ''YES'' THEN 1 WHEN ''NO'' THEN 0 ELSE 0 END as bit) [IsNullable]
              ,   CASE
              WHEN c.DATA_TYPE in (''varchar'', ''nvarchar'', ''varbinary'') and
              c.CHARACTER_MAXIMUM_LENGTH = -1 THEN
              c.DATA_TYPE + ''(max)''
              ELSE
              c.DATA_TYPE
              END
              as [TypeName]
              ,   c.CHARACTER_MAXIMUM_LENGTH [MaxLength]
              ,   CAST(c.NUMERIC_PRECISION as integer) [Precision]
              ,   CAST(c.DATETIME_PRECISION as integer) as [DateTimePrecision]
              ,   CAST(c.NUMERIC_SCALE as integer) [Scale]
              ,   c.COLLATION_CATALOG [CollationCatalog]
              ,   c.COLLATION_SCHEMA [CollationSchema]
              ,   c.COLLATION_NAME [CollationName]
              ,   c.CHARACTER_SET_CATALOG [CharacterSetCatalog]
              ,   c.CHARACTER_SET_SCHEMA [CharacterSetSchema]
              ,   c.CHARACTER_SET_NAME [CharacterSetName]
              ,   CAST(0 as bit) as [IsMultiSet]
              ,   CAST(columnproperty( object_id(quotename(c.TABLE_SCHEMA) + ''.'' + quotename(c.TABLE_NAME)), c.COLUMN_NAME, ''IsIdentity'' ) as bit) as [IsIdentity]
              ,   CAST(columnproperty( object_id(quotename(c.TABLE_SCHEMA) + ''.'' + quotename(c.TABLE_NAME)), c.COLUMN_NAME, ''IsComputed'' ) | CASE WHEN c.DATA_TYPE = ''timestamp'' THEN 1 ELSE 0 END as bit) as [IsStoreGenerated]
              ,   c.COLUMN_DEFAULT [Default]
              FROM
              INFORMATION_SCHEMA.COLUMNS c
              INNER JOIN
              INFORMATION_SCHEMA.VIEWS v ON
              c.TABLE_CATALOG = v.TABLE_CATALOG AND
              c.TABLE_SCHEMA = v.TABLE_SCHEMA AND
              c.TABLE_NAME = v.TABLE_NAME
              WHERE
              NOT (v.TABLE_SCHEMA = ''dbo''
              AND v.TABLE_NAME in(''syssegments'', ''sysconstraints'')
              AND SUBSTRING(CAST(SERVERPROPERTY(''productversion'') as varchar(20)),1,1) = 8)
          ) AS [Extent3]) AS [UnionAll1] ON (0 = [UnionAll1].[C1]) AND ([Extent1].[Id] = [UnionAll1].[ParentId])
    LEFT OUTER JOIN  (SELECT 
        [UnionAll2].[Id] AS [C1], 
        cast(1 as bit) AS [C2]
        FROM  (
            SELECT
            quotename(tc.CONSTRAINT_SCHEMA) + quotename(tc.CONSTRAINT_NAME) [Id]
            , quotename(tc.TABLE_SCHEMA) + quotename(tc.TABLE_NAME) [ParentId]
            ,   tc.CONSTRAINT_NAME [Name]
            ,   tc.CONSTRAINT_TYPE [ConstraintType]
            ,   CAST(CASE tc.IS_DEFERRABLE WHEN ''NO'' THEN 0 ELSE 1 END as bit) [IsDeferrable]
            ,   CAST(CASE tc.INITIALLY_DEFERRED WHEN ''NO'' THEN 0 ELSE 1 END as bit) [IsInitiallyDeferred]
            FROM
            INFORMATION_SCHEMA.TABLE_CONSTRAINTS tc
            WHERE tc.TABLE_NAME IS NOT NULL
          ) AS [Extent4]
        INNER JOIN  (SELECT 
            7 AS [C1], 
            [Extent5].[ConstraintId] AS [ConstraintId], 
            [Extent6].[Id] AS [Id]
            FROM  (
            SELECT
            quotename(CONSTRAINT_SCHEMA) + quotename(CONSTRAINT_NAME) [ConstraintId]
            ,   quotename(TABLE_SCHEMA) + quotename(TABLE_NAME) + quotename(COLUMN_NAME) [ColumnId]
            FROM
            INFORMATION_SCHEMA.KEY_COLUMN_USAGE
          ) AS [Extent5]
            INNER JOIN (
              SELECT
              quotename(c.TABLE_SCHEMA) + quotename(c.TABLE_NAME) + quotename(c.COLUMN_NAME) [Id]
              ,   quotename(c.TABLE_SCHEMA) + quotename(c.TABLE_NAME)                             [ParentId]
              ,   c.COLUMN_NAME   [Name]
              ,   c.ORDINAL_POSITION [Ordinal]
              ,   CAST( CASE c.IS_NULLABLE WHEN ''YES'' THEN 1 WHEN ''NO'' THEN 0 ELSE 0 END as bit) [IsNullable]
              ,   CASE
              WHEN c.DATA_TYPE in (''varchar'', ''nvarchar'', ''varbinary'') and
              c.CHARACTER_MAXIMUM_LENGTH = -1 THEN
              c.DATA_TYPE + ''(max)''
              ELSE
              c.DATA_TYPE
              END
              as [TypeName]
              ,   c.CHARACTER_MAXIMUM_LENGTH [MaxLength]
              ,   CAST(c.NUMERIC_PRECISION as integer) [Precision]
              ,   CAST(c.DATETIME_PRECISION as integer)[DateTimePrecision]
              ,   CAST(c.NUMERIC_SCALE as integer) [Scale]
              ,   c.COLLATION_CATALOG [CollationCatalog]
              ,   c.COLLATION_SCHEMA [CollationSchema]
              ,   c.COLLATION_NAME [CollationName]
              ,   c.CHARACTER_SET_CATALOG [CharacterSetCatalog]
              ,   c.CHARACTER_SET_SCHEMA [CharacterSetSchema]
              ,   c.CHARACTER_SET_NAME [CharacterSetName]
              ,   CAST(0 as bit) as [IsMultiSet]
              ,   CAST(columnproperty( object_id(quotename(c.TABLE_SCHEMA) + ''.'' + quotename(c.TABLE_NAME)), c.COLUMN_NAME, ''IsIdentity'' ) as bit) as [IsIdentity]
              ,   CAST(columnproperty( object_id(quotename(c.TABLE_SCHEMA) + ''.'' + quotename(c.TABLE_NAME)), c.COLUMN_NAME, ''IsComputed'' ) | CASE WHEN c.DATA_TYPE = ''timestamp'' THEN 1 ELSE 0 END as bit) as [IsStoreGenerated]
              , c.COLUMN_DEFAULT as [Default]
              FROM
              INFORMATION_SCHEMA.COLUMNS c
              INNER JOIN
              INFORMATION_SCHEMA.TABLES t ON
              c.TABLE_CATALOG = t.TABLE_CATALOG AND
              c.TABLE_SCHEMA = t.TABLE_SCHEMA   AND
              c.TABLE_NAME = t.TABLE_NAME       AND
              t.TABLE_TYPE = ''BASE TABLE''
          ) AS [Extent6] ON [Extent6].[Id] = [Extent5].[ColumnId]
    UNION ALL
        SELECT 
        11 AS [C1], 
        [Extent7].[ConstraintId] AS [ConstraintId], 
        [Extent8].[Id] AS [Id]
        FROM  (
        SELECT
        CAST(NULL as nvarchar(1))     [ConstraintId]
        , CAST(NULL as nvarchar(max)) [ColumnId]  
        WHERE 1=2
      ) AS [Extent7]
        INNER JOIN (
          SELECT
          quotename(c.TABLE_SCHEMA) + quotename(c.TABLE_NAME) + quotename(c.COLUMN_NAME) [Id]
          ,   quotename(c.TABLE_SCHEMA) + quotename(c.TABLE_NAME)                             [ParentId]
          ,   c.COLUMN_NAME   [Name]
          ,   c.ORDINAL_POSITION [Ordinal]
          ,   CAST( CASE c.IS_NULLABLE WHEN ''YES'' THEN 1 WHEN ''NO'' THEN 0 ELSE 0 END as bit) [IsNullable]
          ,   CASE
          WHEN c.DATA_TYPE in (''varchar'', ''nvarchar'', ''varbinary'') and
          c.CHARACTER_MAXIMUM_LENGTH = -1 THEN
          c.DATA_TYPE + ''(max)''
          ELSE
          c.DATA_TYPE
          END
          as [TypeName]
          ,   c.CHARACTER_MAXIMUM_LENGTH [MaxLength]
          ,   CAST(c.NUMERIC_PRECISION as integer) [Precision]
          ,   CAST(c.DATETIME_PRECISION as integer) as [DateTimePrecision]
          ,   CAST(c.NUMERIC_SCALE as integer) [Scale]
          ,   c.COLLATION_CATALOG [CollationCatalog]
          ,   c.COLLATION_SCHEMA [CollationSchema]
          ,   c.COLLATION_NAME [CollationName]
          ,   c.CHARACTER_SET_CATALOG [CharacterSetCatalog]
          ,   c.CHARACTER_SET_SCHEMA [CharacterSetSchema]
          ,   c.CHARACTER_SET_NAME [CharacterSetName]
          ,   CAST(0 as bit) as [IsMultiSet]
          ,   CAST(columnproperty( object_id(quotename(c.TABLE_SCHEMA) + ''.'' + quotename(c.TABLE_NAME)), c.COLUMN_NAME, ''IsIdentity'' ) as bit) as [IsIdentity]
          ,   CAST(columnproperty( object_id(quotename(c.TABLE_SCHEMA) + ''.'' + quotename(c.TABLE_NAME)), c.COLUMN_NAME, ''IsComputed'' ) | CASE WHEN c.DATA_TYPE = ''timestamp'' THEN 1 ELSE 0 END as bit) as [IsStoreGenerated]
          ,   c.COLUMN_DEFAULT [Default]
          FROM
          INFORMATION_SCHEMA.COLUMNS c
          INNER JOIN
          INFORMATION_SCHEMA.VIEWS v ON
          c.TABLE_CATALOG = v.TABLE_CATALOG AND
          c.TABLE_SCHEMA = v.TABLE_SCHEMA AND
          c.TABLE_NAME = v.TABLE_NAME
          WHERE
          NOT (v.TABLE_SCHEMA = ''dbo''
          AND v.TABLE_NAME in(''syssegments'', ''sysconstraints'')
          AND SUBSTRING(CAST(SERVERPROPERTY(''productversion'') as varchar(20)),1,1) = 8)
      ) AS [Extent8] ON [Extent8].[Id] = [Extent7].[ColumnId]) AS [UnionAll2] ON (7 = [UnionAll2].[C1]) AND ([Extent4].[Id] = [UnionAll2].[ConstraintId])
    WHERE [Extent4].[ConstraintType] = N''PRIMARY KEY'' ) AS [Project5] ON [UnionAll1].[Id] = [Project5].[C1]
WHERE  NOT (REALLY LONG PARAMETER LIST INVOLVING MOST TABLE NAMES)