Replication taking too much time between requests
What could/should we do?


Discard the assumption of synchronous replication and redesign your application accordingly. Replication was never designed for this. Latency of hours can happen and you should design accordingly.

None of the existing SQL Server technologies, including Availability Groups readable secondaries in synchronous commit mode, make a guarantee of synchronous propagation of changes to replicas/secondaries. the only place from where you can read back your own changes and be guaranteed to see your own changes is the publisher/primary, where the changes were made in the first place. Any expectation to the contrary is folly.