Need help in troubleshooting slow MSSL DB

Hi All, Need help in trobleshooting a slow database. One of our customer setup having below configuration is performing very slow. Customer setup configuration:  OS: 64 bit Windows 2008 server machine DB: 32 bit Microsoft SQL Server 2008 R2 Express edition. RAM: 8 GB DB size: 4 GB We tested one of our local test DB on same configuration, which is performing good. The same query on customer DB and our test DB shows different execution plan. In the customer DB the execution plan shows that DB is not picking the right index for queries which is causing more delay in execution. On specifying option(recompile) the query execution is very fast. The queries are tested on much higher table size (80 million records) and are found to be fast on local machines and other customer setup. Is there any DB propery or configuration which may cause this behaviour for slow db? < ...