Xsyon believes that certain actions are causing the lag, they are rebooting the server to add more diagnostics to identify which ones, and will hopefully be able to identify the offending actions. They can then work out a way to prevent this. Perhaps cooldowns on certain activities or something else.
Anyway, wanted to spread the word...
Edit - This is no way an official statement but due their workload I think we as a community can help them concetrate on fixing the problems and I know some people many not be in game as they furioously work their little butts off
What was said was that it's specific actions that necessitate a backup ending up bottle-necking the data the more they're queued. The fix will not be to slow terraforming/whatever else down 10 fold (or at least, shouldn't be). The checks they're putting in place are to allow them to monitor specifically what is happening at the bottleneck(s) and find a solution in the code. Let's hope it doesn't take much longer, eh?