Quick overview, I was seeing long waits on a specific distribution agent. It would do a 10 second page latch wait on msrepl_commands (retrieving commands), then another 10 second wait on waittype PREEMPTIVE_OS_WAITFORSINGLEOBJEC. I assume this is waiting on the external distagent.exe to apply commands at the subscriber.
Tracing on both sides gave me different results though. sp_MSget_repl_commands duration qas quick, as was each ins/upd/del on the subscriber side. I decided to stop and start the dist agent, and now everything is performing optimally, no more long waits on either side.
Anyone ever seen this, or have any idea what was going on? I'd love to know what I fixed by accident. Thanks all.