Relatively larg data on client side in web application

well we are discussing on building a web application where (as per clients requirment) there will relatively large data (60,000 items) to be shown as tree view

lets assume each item is string of 500 characters .

My questions is about maintaining such data on client side.

Basically this is an over kill to be used in asp.NET web form with viewstate (correct me if i am wrong)

what are better options of handling such huge list of items with providing sorting and searching ability on them

I was thinking bring them once and keep them in local storage but then found out local storage to be limited to 5MB and its clear that we need more