Performance Issues

The following sections discuss advantages and disadvantages of 64–bit performance.

64-bit Application Advantages

• Arithmetic and logical operations on 64-bit quantities are more efficient.

• Operations use full-register widths, the full-register set, and new instructions.

• Parameter passing of 64-bit quantities is more efficient.

• Parameter passing of small data structures and floating point quantities is more efficient.

• Additional integer and floating point registers.

• For amd64, PC-relative addressing modes for more efficient position-independent code.

64-bit Application Disadvantages

• 64-bit applications require more stack space to hold the larger registers.

• Applications have a bigger cache footprint from larger pointers.

• 64–bit applications do not run on 32–bit platforms.