From the information you have shared, there is nothing we can do to assist, but give some advice for troubleshooting.
You will need to get hold of which queries that are also. You say that updating statistics helps. It would then be a good idea to get the query plan before and after the statistics update. It may not be the case that the statistics update really matters. Next time just do "sp_recompile tbl" and see if this has any effect. That would suggest that it is a parameter-sniffing issue.
What the actual solution would be is to early to say. You need to find information first.