Graal v4 will be faster, it should be ok even with 32 bit
Compiling for 64 bit can increase the speed, but we would also need to get the good 64 bit libraries and such to be really faster, also buy new compiler licenses, which can be a lot of money.
For 64bit Linux we plan to compile a version soon though, that platform is also more stable and more used already, and compilers and libraries are 64 bit.