then look for what changed.

Rebooting might solve it. Network trouble could potentially explain it (dropped packets and all that).

My first guess would have been that certain coding techniques were used (eg using recordsets in VB without realizing that that sends an update once per field per row, which really adds up), though your insistance that normally you go much faster suggests that that isn't your problem.

Also note that Sybase (and therefore likely SQL Server) will slow down drastically once a row of data no longer fits in a single packet. But IIRC, drastically is a factor of 4-5, not several hundred.

Cheers,
Ben