How can I reduce the time until I get the newest block ? Does the number of the outbound peers affect the speed?
Up until the latest release (v0.9.3), more peers actually means slower synchronization typically, because we only really fetched from a single peer.

The upcoming release (v0.10.0) has a completely rewritten block fetching/validation mechanism, which first validates headers, and then fetches the blocks from all peers in parallel. The result should be much faster synchronization.