Form Slowness in production environment

Hi All, 


i am trying to open a form in Production environment from Accounts payable with 1000+ data lines in it. it takes a long time more than 10 to 15 min, but the same form in UAT with same amount of data runs with in 1 min.

i have compared the code and found no difference and i did re-indexing in SQL too but its not working. Please let me know what is causing the slowness and how to resolve the issue.