small changes to slony can improve
performance a lot during replicating over wan high-latency link.

1. fetch more than 100 lines at once becase fetching over WAN is slow
  its easy to compute average line size and then fetch for example +- 1MB
  of log lines. 

2. Can pgsql use gzip compression for data transfers?

not related to wan but
3. consider to use prepared statements for updating subscribed tables