I personally use the first method, and have never had an alt-tab related crash since using it (about a year now). Credit to rddit u/Juulk9087 for his advice for Streamers post here: https://old.reddit.com/r/GlobalOffensive/comments/1aijdfl/i_set_out_on_a_mission_to_make_it_so_you_can_alt/

___________________________________________________________________________________________________________________________________

Disabling CS2 auto minimizing

In cs2_video.txt (buried in steam\userdata), changing:

    "setting.nowindowborder" 1
    
    "setting.fullscreen_min_on_focus_loss" 0

This makes the game Not Bloody Minimize, which is I think the issue, because when paired with the default engine_no_focus_sleep setting, sets the game to very low fps and minimizes. In autoexec.cfg, I've set

    engine_no_focus_sleep 0
 which makes the game play normally when alt-tabbed.  

The cs2_video.txt file is located here:

    Steam\userdata\(Your SteamID3)\730\local\cfg\

This method has two caveats, which are you need to hold ALT when ALT-TABBING until the window you want is in focus. takes 1 extra second. Otherwise the CS2 window remains in front, despite not being the active window. Also, ANY changes to graphics options will reset these two values in cs2_video.txt; therefore, after making changes I set my file to read-only.

___________________________________________________________________________________________________________________________________

Resolution matching

Some use a script which changes the desktop resolution to another one, if not using native (such as stretched or lower than native) before launching the game. Credit to reddit u/aveyo for this one: https://www.reddit.com/r/GlobalOffensive/comments/1g56n34/cs2_launcher_script_update/

___________________________________________________________________________________________________________________________________

Borderless Windowed

This is vastly improved over CSGO. CS2 uses the DXGI flip model, which doesn't introduce extra system latency by rendering the desktop & everything else like CSGO used to do. it's available in DX10 onwards, ie also DX11 and DX12. That's why Exclusive Fullscreen isn't a thing in new games - borderless windowed is so much better than it used to be.

For this method, it required this setting in Windows 11. Win 10, I'm really not sure about. 

System > Display > Graphics. Turn on "Optimizations for windowed games".

https://images.steamusercontent.com/ugc/11927930071060212/C7BCD8EF6D451E115CF00DF7FA1C6C4238A7EB0F/