hlc.PhysicalNow and hlc.PhysicalTime provide access to the hybrid logical clock's physical component. Accessing the hlc's state is expensive because it requires a lock acquisition for a lock which is fairly contended. As such, we should be deliberate when using the hlc and avoid using it when possible.

In a lot of cases, a system clock is more than sufficient and should be a lot cheaper. These cases include access to time in the:

• StorePool
• (storage: Eliminate use of hlc.Clock in replicaStats #30651/@a-robinson) replicaStats
• (TODO/@nvanbenschoten) replica.lastUpdateTimes
• (TODO/@andreimatei) TxnCoordSender.Send and TxnCoordSender.maybeSleepForLinearizable
• rpc/breakerClock and rpc/Context
• connExecutor all over the place
• RuntimeStatSampler
• MetricsRecorder
• authenticationServer
• log.selectEventTimestamp
  ... maybe others ...

We should audit uses of the hlc clock and make sure they actually need the added semantics it provides.

EDIT: the direction of this issue has changed. See #30520 (comment).