How to Optimize LINQ Queries for Large Datasets?

I’ve been working with Entity Framework Core 7 and noticed performance degradation when querying tables with over 2 million rows. What techniques can I use to keep LINQ queries fast? Any tips on indexing, projection, or server‑side evaluation would be appreciated.

Use deferred execution wisely. Only materialize results when needed. Avoid .ToList() before you’ve filtered everything. Also, project only the columns you need with .Select() to reduce data transfer. Consider adding appropriate indexes on the columns used in where/join clauses. If you’re doing complex calculations, move them to the database side with .AsQueryable() and let EF translate them.

Another trick is to batch large result sets. Instead of pulling all rows at once, use .Skip() and .Take() with a reasonable page size. Combine that with async enumeration (await foreach) for streaming large datasets without loading them all into memory.