connection initialization...tuning initcwnd

OK, so server side, if you are using Linux kernel 2.6.38 or later the default initcwnd and initrwnd increases from 3 to 10. If you are using this version or later, set your settings in the TCP profile assigned server side to 10 to match this. If you're not using this version or later, upgrade. If you really can't just google on how to change these settings manually. You'll also need to disable slow start.

Upgrade to kernel 3.2 or higher if you can, there are lots of good, worthwhile performance improvements.

If none of the above are possible, on any version, use: sysctl –w tcp_slow_start_after_idle=0 to stop slow start messing with long lived connections.

That's it where you've reliable networks really.