C13 Massive CPU spikes - change buffer fix?

I have been getting some massive CPU spike even in simple Projects with just 5 tracks , these only happen while in record (live playback)

I noticed that if I change the Buffer to any other size and then change it back to the same one as before its fixed !!!

No Audio as this is a screen grab , but you can see I am just playing single notes one after the other to trigger legato mode …

After the above test , I then select the track below and found again massive CPU spike until changing the Buffer from 128 to 192 , then back to 128 ?

this is very odd -