How can external website mashups help large object data performance in Salesforce?

External website mashups enhance large object data performance in Salesforce by providing references without harming performance. This approach allows Salesforce to utilize data and functionality that exist outside the platform, effectively minimizing the need to store large volumes of data directly within Salesforce itself.

When external data is referenced instead of stored, it reduces the load on Salesforce's own data storage and processing capabilities. As a result, users can access real-time information from the external source without the overhead associated with managing large datasets internally. This strategy ensures that performance remains smooth and efficient, as it leverages existing infrastructure while maintaining the integrity and responsiveness of Salesforce applications.

The other options suggest limitations or methods that might not address the performance issues associated with large object data, making them less effective for this purpose. By focusing on referencing external data rather than importing or restricting access to data, the selected approach optimally supports high-performance requirements.