Dserver: chaotic performance graph

[super-truite]

I have more and more the dreaded "Multiplayer server overload". I get it with 1 player, 10 moving AI tanks, 4 AI planes and something like 30-40 static AT/AAA guns, entrenched AI tanks etc. Most of the tanks are now replaced by "AI non playable tanks", which should save some resources. The server is a quite good dedicated one (i7-7700K with up to 4.5 GHz). 
When looking at the performance graph, I see that the average performance is ok, but that some little spikes are exceeding the limit:

 

Is this a typical graph or is something fishy going on ?

[super-truite]

hmm, in fact on my computer I get more stable performances with the same mission:

(spikes are the start of missions). 

I could get an AMD Ryzen 7 3800X  instead, but it is more expensive. Is this better for il2 (compared to i7-7700K)?