Have you tried inserting a tracer token to verify where the delay is actually occurring?

You can also create custom alerts (in your SQL Server Agent >> Alerts) via the SSMS, and in the Replication Monitor (they kind of go hand in hand).

You can also create your own little "custom-baked" process to monitor the latency between your publisher/distributor/subscribers (I implemented this at our shop at it works quite well). If you're interested I can post those scripts...