If "It's a very busy app and is running into crashes due to out of memory exceptions at these sites", then clearly you cannot stay with 32 bit mode. "Not only its compatibility better than the native 64-bit, performance and memory consumption are also better" is rather an advice for small web apps that won't take too much memory. You can find quite a lot of discussions years ago when everyone migrate from 32 bit to 64 bit, (like https://stackoverflow.com/questions/2378399/are-64-bit-programs-bigger-and-faster-than-32-bit-versions)
Microsoft uses similar reasons to delay the creation of 64 bit Visual Studio for Windows, citing how 64 bit version does not give better performance, but in 2021 they create VS2022 a 64 bit version and sell it hard.
BTW, stay away from web gardens. In your case, 64 bit pools and load balancing setup are necessary to handle heavy load.