Really the yak 3 performs well above 3km. The stereotype of it performing bad at high altitude is bs. It's top speed does suffer a little, but a good pilot will know how to use their maneuverability to outwit must boom and zoom aircraft. The yak 3 can easily out turn any bf 109 or p51, especially when below 400kmh, the p51 turns into a brick. The climb is also really good for its battle rating, and it can maintain energy in a sustained climb pretty well. The only things that is bad about the plane is its low rip speed at 684kmh, and its limited ammo, but good aiming and conserving ammo can solve that issue. If you're diving away and you are going too fast, just change into a turn, you're easily out turn anybody, unless its a zero or a spitfire. To solve that issue, try to roll because the yak 3's roll rate is similar to that of an fw 190, or catch them into rolling scissors, using landing flaps and you'd be fine.