Why temp tables are faster than table variables

Temp tables usually perform faster because SQL Server maintains statistics on temp tables, allowing the optimizer to estimate rows accurately and choose efficient execution plans, joins, and memory grants. Temp tables support full indexing and parallelism, so they scale better for large datasets and complex queries.

Table variables do not maintain statistics (except limited improvements in SQL Server 2019), so SQL Server often assumes they contain only one row, producing poor execution plans and slower performance. Therefore, for real workloads, temp tables often outperform table variables.

Even though many people assume table variables are faster, in real-world systems temp tables are often faster. The reason is not “magic” … it is because of the SQL Server Execution Engine behavior, statistics, optimization, and TempDB internals. Table variables are designed to be lightweight, they hide critical info from the optimizer, which leads to BAD execution plans.