When I open the RBMK for a while,it seems like that it causes a lot of lag.If I stand near it,I can't open anything's GUI immediately.I have to for a while.And the item won't drop immediately also when I mine a block.Sometimes I even can't move as I am always sent back.The only way to get rid of this is shutting down the RBMK or geting away from it for a while.
This problem happened just in the recent versions(3990-3997).So I wonder whether if there is a BUG.Please Help :..(

The RBMK hasn't been changed in the versions you named, or shortly before that, nor have I received any other reports of it being unusually laggy. Have you run the debugger before?

Do I have to enable the debugmode in the config file?

The debugger is a vanilla feature, all you have to do is run /debug start to start a debugging session, wait for it to collect data (i.e. reproduce the lag) and then /debug stop. In your game's files, there should now be a folder called debug with text files of the debugging results. Those include the time it took for game ticks, which blocks took what specific amount of time to update and all that.

Here is the debug file:
profile-results-2021-09-22_15.38.56.txt

Do I have to update more thing?

Please check for this issue in the current versions of HBM's Nuclear Tech mod, if it still persist please make a new issue thread regarding this, if not then don't

it be best to close this issue regardless of the outcome