The query is: 

```
CREATE TABLE logfile (
   sequence_number BIGINT,
   start_time DECIMAL,
   finish_time DECIMAL,
   irp_major VARCHAR(100),
   offset BIGINT,
   length BIGINT,
   filename VARCHAR(2000),
   is_seq BIT 
   );
//bulk insert 120 000 rows
CREATE CLUSTERED INDEX IX_logfile ON logfile(sequence_number); 
UPDATE dbo.logfile SET is_seq = (
SELECT  CASE WHEN a.offset = (b.offset + b.length) THEN 1 ELSE 0 END AS seq
FROM    dbo.logfile a
        LEFT JOIN dbo.logfile b
            ON a.sequence_number = b.sequence_number + 1
WHERE a.sequence_number = logfile.sequence_number)

```

Is there anyway I can improve the performance of the update query?