P-36 was the most successful aircraft in the battle of France,Outperforming even more modern Dewoitine d.520.
Why was this seemingly medicore plane performed so well in 1940?
As mentioned, speed, but also reliability and effective armament. And not actively trying to kill the pilot.
The MB.152 had engine overheating problems that were never fully solved. It had mostly cured the tendency of diving MB.150s and 151s to push into even-deeper dives until they crashed, but that was still a scary prospect. It also had somewhat heavy controls and was not amazingly agile. The wings were too flexible for the high recoil of the HS.404 and the pneumatic firing system had both a painfully long activation time and delays for each of the four guns to fire (0.5 seconds for the gun with the shortest pneumatic line, up to 2 seconds for the longest).
The MS.406 was significantly slower than the Hawk 75, but at least as agile: it was known as a real pilots airplane. However, they had been in services for a relatively long time, most were worn out, and spare parts were in ever-shorter supply, especially for the engines (Hispano-Suiza was devoting all of its effort to building engine for new aircraft). It also suffered from engine overheating problems, in its case because of a terrible radiator design that seriously reduced its top speed.
Both aircraft were handicapped by their armament. The wing-mounted MAC machine guns were drum-fed, which seriously limited their ammunition capacity. The HS.404 evolved into the famous Hispano-Suiza cannon that saw widespread service over many years, but in 1940 it was suffering serious teething issues. It was also drum-fed, but the exceptionally heavy rounds made spring design very difficult. You either had spring that was too strong when the magazine was full, or not strong enough when down to the last 10 rounds (out of 60). This led to many jams, which was more than frustrating because the Hispano-Suiza provided almost all of the firepower of the MS.406 and MB.152. Some units figured out that they could load just 50 or 55 rounds and largely eliminate jams, but that was a big reduction in carried firepower. The HS.404 also suffered from inconsistent manufacturing, design flaws, or both that cause wide variations in RoF among guns. Slow guns fired at about 2/3 the rpm of fast guns, and none met the design rpm, although the fastest guns came close.
The Hawk 75 was blessed with a reliable engine and adequate cooling.
The Hawk 75 was seriously handicapped by only carrying rifle-caliber MGs, but they were FN/Browning belt-fed guns (the famous .30 in 7.5mm), so they had plenty of ammunition. While the Spitfire was still under-armed with 8 rifle-caliber MGs, 2 of the Hawk's 6 were nose-mounted, which made them somewhat more effective, at the cost of RoF. The Hawk 75 could also take a .50 or 11.35mm machine gun in place of one of the nose guns. Variants were available that could mount 23mm Madsen or 20mm Oerlikon cannon in pods that replaced the wing guns, but these were very heavy and increased drag. The Thais ended up removing them because of the reduced performance of the aircraft. Wing racks for 100 lb. bombs were available, which was very handy, as well as a belly rack for a 500 lb. bomb, which was a ridiculous strike capability for a fighter at the time.