What is the performance overhead of Transparent Data Encryption, and how does it compare across different SQL Server versions?

TDE introduces a small amount of CPU overhead since data must be encrypted before being written to disk and decrypted when read back, though modern SQL Server versions have significantly optimized this process, and the overhead is generally considered acceptable for most workloads, though it should still be measured and tested specifically for particularly performance sensitive applications before enabling it broadly.

-- Measure performance before and after enabling TDE
-- using a representative workload test
SET STATISTICS TIME ON;
SELECT COUNT(*) FROM LargeTable;