TTmod's MOTD feature can't cause such issues.
Maybe you have a conflict with some other mod or custom script.

Please upload a server logfile from a session where TTmod was enabled and you've experienced issues so I could take a look.

I tried this solution by setting the time to 9999 and the lag went away for the most part and the server has been running fine for quite a while, but I wanted to update the roads after players had built some new ones since yesterday and I wanted them to show on the map. I ran the RCON command included to update the road layer and now have no roads at all showing in Livemap, not even the original ones. All other layers in map work fine, buildings, players, etc.

Help?

Road update takes up to 5 minutes. Maybe it was interrupted due to server restart.
TTmod updates the road layer on every server restart anyway. There's no necessity to update it manually unless you have no daily restarts scheduled.
If the issue persists after next server restart, please upload a recent server logfile somewhere I can review it. Thanks.

This whole thing has now been removed in TTmod 1.3
https://nyuton.net/ttmod-1-3-released/

The livemap will take care of it by iteself.