C#.net performance

Question

I have an issue about a C#.net 2008 perofrmance for on a desktop application. I am basically keeping a desktop form the way it is in production. However, I am changing the database behind in since the production database will change in the future. This desktop application obtains all of its data from stored procedures.
When I ran the new version of the code, the application timed out when it needed to display a large number of records. However it does work when you ask for a limited number of records.
The old production sql uses nolock on the two tabes it joined together. Thus i decided to use nolock on all the 10 new tables that i joined together. The new version of the application does run faster with the nolock. Can you tell me why?
Also the new test version of the application, now returns all the rows requested. However, the application looks like it is going to stop. You see on the screen that the application is not repsonding. If you wsait long enough, you will see all the rows that were requested. The desktop form also 'flashes' when it brings back all the data. Thus, can you suggest what I can do to keep the application from looking like it will not respond and then flashes. Should I use less than ten nolock statements in the stored procedure? Is there some of sql statement i can use?