Hello Martin,
15 hours looks more than expected for me. You may want to check tips to improve this time by reading the documentation about Improving Dump or Load performance:
Improving Dump or Load Performance
I wonder which option of the sybrestore are you using?
When using the interactive mode, the idea is to do regular log transaction dumps, so, you shouldn't always restore the complete database(Example of Restoring a Database to a Point In Time).
HTH
Cris