Only happen with one project, others the performace is identical to the offline play when I join. What thing could cause that?
Literally anything. Sharing the stats in the profiler could help narrow down the cause. Put #define DEBUG anywhere in your code, run the game, go into the console (default F1) and click server -> profile. Click Start and play the game for a little bit. Hit Refresh and then post a screenshot of the results here.
In response to Reformist
Offline vs Localhost
Lag may be the wrong word, it's more like a wrong frame skip. I tried disable procs and decrease the size of the map. I'll keep trying some things.
In response to Reformist
Reformist wrote:
Put #define DEBUG anywhere in your code,

You can't do that now. If it's not in the main .dme that #define line will no longer do anything.

Can you see the difference? They were recorded under the same conditions, but it's a bit different in reality. It happens with different designs and different modes of move.