You'll have to clarify that.
In most cases, Read Committed will peform just fine. In a few, Read Committed Snapshot, or Snapshot, will perform better. In a few Serializable will actually perform better.
It all depends on what you're doing with the data, how the data is structured, and what you expect applications and users to want from the data and application(s).
If what you're looking for is some sort of recommendation that Read Uncommitted or NoLock will "perform better", you won't get that, because it's false. If you're fishing for that recommendation (I don't know if you are or not), then I'll say what I say ever time that comes up. Yes, it can be faster in some circumstances, so long as you don't mind getting wrong data slightly faster. And it's not faster than other isolation levels (RCSI or SI are often just as fast or faster, so is RC under many circumstances). Sometimes it is, but "fast and wrong" isn't a good solution in the vast majority of cases.
So, performance and locking characteristics really depend on your situation. There is no "Run Faster" option in SQL Server.
- Gus "GSquared", RSVP, OODA, MAP, NMVP, FAQ, SAT, SQL, DNA, RNA, UOI, IOU, AM, PM, AD, BC, BCE, USA, UN, CF, ROFL, LOL, ETC
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