Optimizing Netwide Assembler codes in Microsoft Windows

I will will appreciate if someone could review these NASM assembler code for me. Is about encoder decoder. The encoder performs the following:

• pads the shellcode with NOP opcodes so it is 4 bytes aligned
• a random byte is generated for each 4 bytes of the shellcode
• the 4 bytes are put in the reverse order and XORed with the XOR byte
• process is repeated until the 0x9090aaaa marker is reached

For those good at NASM assembler for Microsoft Windows, please could you...

Optimizing Netwide Assembler codes in Microsoft Windows