One other important factor to keep in mind. The best Western, and to some extent Japanese and German aircraft, were designed somewhat for universal combat environments. With some exceptions, they could fight high or low, they could fly escort or air superiority missions, and could contend with enemy fighters, strike aircraft, or heavy bombers - the latter requiring very heavy armament
Soviet aircraft in general, and their fighters in particular, were not designed for universal conditions. They were designed specifically for the battlefield in Eastern Europe and Western Asia. They were designed to endure very rough field conditions, to withstand truly extreme cold, (and considerable heat during the summer in the southern part of the Theater). They were made in full knowledge of the conditions of the war - the high loss rate. They carried relatively few guns, often just one or two (though usually at least one autocannon, and their cannon were very good). Their guns were in the nose and their doctrine advocated shooting from short range. They didn't carry a lot of ammunition. They did not have two stage or multi-speed superchargers, so most of their planes did not perform well above 12-15,000 ft. This limited their top speed.
But for the Soviets, since they were not doing or contending with much Strategic bombing, (and that mostly at night), and did not have to deal with real heavy bombers ala B-17, they were not interested in high top speed at 25,000 ft. They wanted planes that were fast at 5,000 and 10,000 feet, to cover the front. That is what the VVS means - frontal aviation. Their job was to shoot down German fighters and Stukas, and Ju-88s and various other light and medium bombers. To strafe enemy ground troops and shoot rockets at them.
They were highly tailored to this role. They were (mostly) made of laminated plywood of ubiquitous birch, extremely plentiful in Russia. They used a minimum of metals in their construction, though they did have armor. They were fast and agile down low, small and low-drag (assuming the manufacturing problems were sufficiently sorted out, and the pilot kept the windscreen on). Smaller planes make smaller targets and are harder to spot.
Many around here judge Soviet aircraft by Western standards. A Yak-3, the argument goes, is inferior to a P-47, because it can't fight at 35,000 ft, and it only has three guns, and it has short range. The Soviets, notably, were offered the P-47, but they almost laughed at it. Thought it was an interesting and well made aircraft, but that it was "not a fighter". They could have had as many P-47s as they wanted. Theirs were better for their own role. Even the Spitfire was relegated to air defense (PVO) units, as it didn't do very well on the front line battlefield.
The Soviet aircraft were optimized for the environment. They were cheaply made, almost to the point of being disposable, which many of them were. The Soviets lost 46,000 combat aircraft in WW2. At that rate, they could not afford to put leather seats in each one. The Germans lost somewhere around 10 -25,000 planes on the Eastern front too (the exact figure is still debated). The German planes were a lot better made, with more features. More instruments on the control panel, better engines. More guns. And also much more expensive in terms of work hours to build them, and strategic materials like aluminum and steel. Their pilots and aircrew were more "expensive" to train as well.