Like in RaceChrono Pro app (Live lap timer, android) or deltabar in iRacing, where delta is displayed continuously. It is a great tool for driving skills improvement, simple, but effective.
+best lap could be stored with reference to setup to track positive changes in tuning the car.

BR,
Alex

LFSLazy has a similar function that compares your current lap with your personal record updated in yout LFSW, have you tried it?

https://www.lfs.net/forum/thread/85771-LFSLazy

It's similiar to the assetto corsa prediction lap timer, but in my opinion more complete.

The only drawback for me is that always compares with your personal best, not with your best lap on your current race like in assetto.

Lets try, thanks