Well, the second you do any database call or other service call you've already spent 100x longer doing that than you have recording some timings. These clients

Well, the second you do any database call or other service call you've already spent 100x longer doing that than you have recording some timings. These clients will usually buffer the stats in memory and push them out asynchronously. Performance is definitely affected but I'm pretty sure it's negligible for most cases. Best practice would be to reduce tracing ratio in production too. So most requests are literally just a timing.