sql server replication: The client production server CPU starts thrashing. Task manager indicates
that SQL server is gobbling CPU cycles. Having a look at the replication
monitor, it is obvious that indivual synchronisations to the mobile devices
are taking significantly longer expected.

Observing an indivual synchronisation attempt, the Upload changes to
Publisher rows are very quickly resolved.

The Download changes to Subscriber seems to take up a very long time.

Along the way, the estimated completion does a few interesting things, like
going from 100% complete with no estimated time to complete, back to
seomthing like 77% with 2 minutes left to complete.

This sort of behaviour occurs when there are only a hundred rows to download.

Synchronisations for minimal amounts of data suddenly taking anywhere from 2
to 15 minutes. Totally unacceptable form the client perspective but seems
that 2005 behaves quite different from 2000 and the tricks are yet to reveal
themselves.

Note - It is a server hardware issue as there is in excess of 3 GB ram, the
database is on a SAN and there are 4 3Ghz CPUS in operation.

Steve,
I'd probably raise a PSS call for this. You could use profiler/dbcc
inputbuffer etc to try to determine what the issue is, but this sort of
debugging is routinely done by PSS and you might have uncovered a bug they
alreadty know about.
Cheers,
Paul Ibison SQL Server MVP, www.replicationanswers.com
(recommended sql server 2000 replication book:
http://www.nwsu.com/0974973602p.html)