9.9.0 / 2026-07-30

• perf(document): improve toObject perf with faster string checks and avoiding unnecessary isSelected on paths with no getters #16407 #16373 #16385
• perf(model): improve insertMany() performance and general change tracking performance #16370
• perf(timestamps): avoid adding $setOnInsert for createdAt unless upsert set #16411
• perf: improve toObject() performance #16408 #16405 #16378 #14394 BIGSUS24
• types: add discriminator key to each member of embedded discriminator enum- #16412 #16045