I am projecting new application what has big tables on pages. Something like contacts. (ca 2000-6000 records to view same time; and every record has 10-20 fields to show) I want that all table can be edited (add keyword(s) to every record, note(s), etc) I can filter data in grid. And can fill all column by same value or by some rule. Can edit every record separately. Something like simple version of Excel or Access DB

At the moment I have app what does almost everything needed (did it with dhtmlX components ; JS/AJAX+PHP), but over 2000 records on page it will be so slow that changing info and saving to server will take 1-3 minutes to wait before anything happens. There is no difference what browser I use. With these dhtmlX components I cant use pagging, because then I cant change all data same time. I can change only data on current page.

I dont know now how to do application react quicker than now? Should I use C# and ASP technology? Or do Win.Forms Client-Server app? Can any more experienced give advice/hint/tip what techology to use or how to solve this kind problem?

Sorry my bad English, its not my first language