ESET Smart Security and ESET NOD32 Antivirus version 8 and earlier are hybrid programs in that they contain both 32-bit and 64-bit program code. The engine and interface modules used by your ESET security product to protect a system from malware are the result of years of development to create highly-optimized x86 assembly language code. During testing, it was discovered that recompiling certain portions of the program to 64-bit code resulted in increased memory usage with no discernible improvement in performance, stability or reliability.
When a 64-bit interface needs to be monitored, such as for on-access or Windows Socket layer scanning, 64-bit code is used. As evidenced by the high scanning throughput and detection rate of ESET Smart Security and ESET NOD32 Antivirus under 64-bit operating systems, this does not cause any complications.
In general, the parts of your ESET security product that need to run as 64-bit do, while parts that have no advantage running as 64-bit remain 32-bit code.
ESET Windows home products version 9.x and later are built with native support of 64-bit code.