Hi there,
I don't see how Windows Services can speed up the retrieval of data in a web application. It only adds another layer of overhead.
What you could so is:
1. Optimize the database. Make sure you have optimized indexes on your tables, optimize queries (only select columns and records you need), optimize statistics, use database paging and a lot more. This is a good start:
http://www.google.com/#hl=en&source=...se+performance
2. Cache data that doesn't frequently change. Again, Google is a good starting point:
http://www.google.com/#hl=en&q=cache+data+.NET
Hope this helps,
Imar