Linked Server usage and performances

Experts,

I have some amount of data in SQL Server-1( Database1) and some amount of data in Oracle 10g( Database 2)

I created another SQL Server-2 and tried to access both the servers via linked server and was successful.

The performance of the query/ report is very slow , as the query is executing using Linked server

At this point I don't want to create any tables on SQL Server-2 as the maintenance will become an issue.

I can create views on SQL Server-2.

I tried below approaches.

1. Increased the RAM size from 8GB to 32 GB ( I did not seen any performance increase)

2. Cliconfig - Added Server alias and observed some performance improved.   

Let me know the best approach in terms of performance increase.

Thanks & Regards

Praveen