When I run DBCC SHOWCONTIG, I get the following results

ObjectName:AsyncOperationBase

ObjectId:1724585232

IndexName: cndx_PrimaryKey_AsyncOperation

IndexId: 1

Level:0

Pages:23923

Rows:47204

MinimumRecordSize: 459

MaximumRecordSize: 8051

AverageRecordSize: 3012.731

ForwardedRecords: 0

Extents: 2991

ExtentSwitches: 2990

AverageFreeBytes: 2147.44

AveragePageDensity: 73.4687422782308

ScanDensity: 100

BestCount: 2991

ActualCount: 2991

LogicalFragmentation: 0

ExtentFragmentation: 0.200601805416249

Thank you both for taking the time to look.

I've also googled and found various articles based on this table. They all tend to say performance degrades when this table...

No, it has a clustered index on [AsyncOperationId] which is type [uniqueidentifier]

Thanks David, create table script ....

USE [MSCRM]

GO

/****** Object: Table [dbo].[AsyncOperationBase] Script Date: 05/13/2014 11:00:11 ******/

SET ANSI_NULLS ON

GO

SET QUOTED_IDENTIFIER ON

GO

SET ANSI_PADDING ON

GO

CREATE TABLE [dbo].[AsyncOperationBase](

[MessageName] [nvarchar](160) NULL,

[Depth] [int]...

Thats a massive help, thanks everyone and I will take a look at the articles you have suggested.

thanks again

Apologies for not being clear. This is a trimmed down table definition and some example data...

CREATE TABLE [dbo].[ITEM_SUPERSESSION](

[Superseeded_Item] [char](15) NOT NULL,

[Superseeding_Item] [char](15) NOT NULL,

CONSTRAINT [PK_ITEM_SUPERSESSION] PRIMARY KEY CLUSTERED

([Superseeded_Item]...