Thanks Ze-Jamz,
It was the first time after weeks flying a Bf109 so I probably you are right.
Maybe the Spitfire (I fly mostly the Ia) has the same kind of violent vibrations as well, I do not know, maybe I have not "cooked" a Spit engine until now, you can not do it by overheating the water system (probably it is a bug; I posted it).
The best case I had was "overcooking" a Spit engine by flying too long at max throttle, oil temp exceeded the limit and got a "grosvenor failure" message but even then there were no serious vibrations either...
Of course

it can be due to my superior knowledge and flying skill supremacy when in a Spit or, the abesimal skills and native inferiority of the Bf109 noobs who are trying to cause damage to my superior machine

that I never experienced the same kind of vibrations when flying Spitfires.... (just joking

)
Anyway, I just mentioned it here, it was the first thing that I noticed taking a Bf109 (besides this horrible gunsight aiming disturbance).
~S~
PS. Thank God they fixed the propeller change speed, the Bf109 can do some serious B&Z now