Stored Proc Logical Reads Spiking Daily At The Same Time I have a procedure that I optimized in a dev environment.  It is a heavy lifter and started at 14 millions logical reads with a run time of 30-40 seconds.  I got it down to 96k reads and 8 seconds.  It was pushed to our production database.  Then we noticed that for the last 3 days from 11:30AM-2PM the performance for this proc was tanking with the run time going anywhere from 40 seconds to 2 minutes and the logical read count jumping to 12 million.  

This same query on this same server and DB goes back to 70-95k reads and a couple of seconds around 3PM.  

This issue CANNOT be reproduced in the dev or QA environments and the schema structure is the same between them all and prod. 

At first I thought sniffing or a bad execution plan but that doesnt explain the consistent timing aspect of it all. 

I cant tell if I am over looking something that is staring me in the face or if there is more to the story.  What could cause this read spike?  Any feedback is welcome.
The root was tracked to some old SSIS packages running longer than anticipated. Thanks for the feedback folks!