Port the server from a 32 bit program to a native 64 bit program:
Simply put, a 64-bit processor is more capable than a 32-bit processor because it can handle more data at once. A 64-bit processor can store more computational values, including memory addresses, which means it can access over 4 billion times the physical memory of a 32-bit processor. That’s just as big as it sounds.
In general you may expect a 2-20% performance gain from converting a 32 bit application to 64 bit.
There are 3 most obvious advantages of 64-bit processors over their 32-bit counterparts: extended address space, capacity increase, and larger number of general-purpose registers.

The extended 64-bit address space theoretically allows the processor to work with 16 Ebytes (2^64) of physical memory within the flat memory model. Although contemporary 64-bit processors can address only 1 Tbyte (2^40) of memory in practice, it is still much higher than in the case of 32-bit addressing. A larger amount of available memory, in turn allows you to eliminate or greatly reduce sluggish operations of data swapping to the disk.

The larger number of registers, and increase of their size, allow the processor to handle large memory areas simultaneously, to handle variables and arrays more effectively, and to pass function arguments in registers instead of the stack.
https://pvs-studio.com/en/blog/posts/k0002/