I dont know why the C151 lags more than the C651, from what I
heard, the lag is coming from the grab poles. Seats, I
dunno..
No offense to C151 developer, Willis, but I suggest that if you
would like to test the source of laginess, how about try patching
some of the C151 files with C651 ones (Involves the rename of all
C651 car number related to C151 car number will do, example a
2219.csv to 2131.csv in cars subfolder)
NOTE: This is unofficial way and suggest anyone trying this
should be done on a work folder for test and do BACKUP!!!