As the title suggests, ever since the latest patch i have massive drops in framerate i have never experience before. At first i thought it was my pc only, until i heard other people complaining about it in chat. Some suggest it is tied to the new weather system, the us forum has a thread about it: https://us.forums.blizzard.com/en/heroes/t/main-thread-weather-effects-causing-performance-issues-since-patch-510-june-23-2020/39842
All i can say for me is that it occurs during brawl (which is the only game mode i play) and consistantly shows up during the lvl11-12 phase and them persists towards the end of the game in waves. Framerate drops so low it severely impacts play. For me atleast it doesnt always happen when the weather graphics kick in, but i cant really think of any other graphical or technical thing that has changed in the last patch that would cause something like this.
Edit: Something i remembered is that, i have the game installed on a HDD, when the framerate drop happens, my hard drive is going crazy. Maybe its a loading/location/memory issue?