A typical reason of such issues after the network environment changed is missing/broken routing from the server, where PD4ML runs, to a server where it reads resources (images, stylesheets etc) from. For every external resource link it waits till network connect timeout expired.
To troubleshoot first determine which addresses are not reachable (by setting the debug on). After that you can either resolve the routing/firewall issues or (if the resources can be skip) reduce the JVM network connect timeout to smaller values, like a couple of seconds
my stylesheet doesn't have any outer http link. it seems invoke useTTF api causes taking long time. if i don't invoke useTTF, it is fast but the chinese characters are messed...