Do you use much RoC/Reikas other mods? Later versions of them had absolutely massive improvements to net code. ( A single on was over 400% improvement. )
If so, you can try updating Reikas mods. Be aware that Version 25 makes a couple serious changes though. ( Pretty much all engines require lubricant now, and a lot of it. ) Reikas mods update really well. From Monster 1.1.2 I had a single item ID conflict that I fixed, then the save just complained once that there was some mismatching, but it was only because the naming for a lot of items was tweaked. So, it was basically saying Item: roc8dgearbox can't be found, the itemID matches item: Reika8xDiamondGearbox ( Not the actual names, but you get the idea, they're both the Diamond 8x gearbox, just the naming scheme was improved. )
Also, it may be that the server is being lagged by your client using all of the resources to run at 200 fps.
Can you provide more specific details? Java arguments, the server start command, what kind of stuff you have going on, etc.