Can UPDATE STATISTICS screw up the optimizer?

He have a stored procedure that updates all records in a table in a foreach loop. Within the loop, it selects records from the table it is updating as well as other (static) tables, all with less than 1000 rows. If we do the following: delete all rows in the table update statisticsload 100 rows update statisticsrun the procedure the procedure takes 30 seconds. On the other hand, if we do: delete all rows in the table update statisticsload 100 rows run the procedure it takes 7 seconds!!! Can update statistics actually screw up the optimizer? If so, when? We tried low, medium and high statistics, to the same effect. Platform is Online 7.1 on SCO OSR5, Pentium PRO 200MHz, 128MB RAM. Bashar Chalabi Card Tech Limited bashar@ctl.com