Tune database access speed for a Classic ASP website -- 3

I have a Classic ASP based website which uses DBF files. Some .ASP pages access the database files very quickly, while others have an unacceptably long response time while showing a "connecting..." status message in the browser. They are both using the same database and connection string. It may be that my query string simply needs to be find-tuned. The project will be to analyze and speed up the slow pages using a shared Teamviewer connection to the database and website application.