Hi Lalatendu,
As SumanPramanik mentioned, please have a look at the Attribute Value Protection settings and use the link, he provided, to do the needful in improving performance related to that.
Along with that, I would like to add that, check if the issue is happening for any specific user or not. For one of the affected users, restore the Project List page to the default view and then see if that person sees any improvement in the list page or not.
Thanks,
Abhisek Dhar