Zaephir-Moth: Yes, indeed, "how" can someone fix that occasional horrible lag would be interesting to know...

Edit : Tinkering with the delays values in the "GenericData.dat" file, inside the "Data" subfolder of the game, helps a lot with reducing unecessary animation lag. Choose a set of "Character/Vehicule/Looping Effects/Fire animation delay" values suitable for your rig - after (as usual) backing the original file - and then work from those with the in-game animation sliders. "200", which represents the default one for "Character animation" for example, gives good results on my PC when combined with a 80% level from the corresponding slider. But for "Looping Effects" and "Fire", I need to drop the "1000" defaults down to a much lower number - "400" works great for the general effects and "0", for fire, provided you don't judge the (rising fire) animation delay absolutely necessary, will get you completely rid of any lag whenever you're shooting a Flamer -... Tinker a bit and you should find something suitable fast enough and don't worry : it's completely risk-free.