"Vector path instructions are less efficient than single or double instructions because they require exclusive access to the decoders and pipelines and do not always reorder optimally. For example:
; Example 17.1. AMD instruction breakdown
xchg eax, ebx ; Vector path, 3 ops
nop ; Direct path, 1 op
xchg ecx, edx ; Vector path, 3 ops
nop ; Direct path, 1 op
This sequence takes 4 clock cycles to decode because the vector path instructions must decode alone."
"Vector path instructions are less efficient than single or double instructions because they require exclusive access to the decoders and pipelines and do not always reorder optimally. For example:
This sequence takes 4 clock cycles to decode because the vector path instructions must decode alone."