Sometimes, when you definitely have to squeeze everything from the code, there is only one solution—rewrite it in assembler. My response to any such idea is always the same—don't do it! Rewriting code in an assembler is almost always much more trouble than it is worth.
I do admit that there are legitimate reasons for writing assembler code. I looked around and quickly found five areas where an assembler is still significantly present. They are memory managers, graphical code, cryptography routines (encryption, hashing), compression, and interfacing with hardware.
Even in these areas, situations change quickly. I tested some small assembler routines from the graphical library, GraphicEx, and was quite surprised to find out that they are not significantly faster than the equivalent Delphi code.
The biggest gain that you...