I wonder if it will make a difference if I program with assembly rather than C.

Sometimes it does, sometimes it doesn't.

I, based on an assumption, wrote a display formatting routine in assembler, and when another version had to be done in "5 minutes" did it in C. I found that for that particular function the advantage of assembler was about 5%.

With that, I rewrote another "assumed assembly required" routine in C and there the assembler speed won by a factor of 3

I have found that one of the areas where assembly really help is sequential data fetch since the compiler seems to have a problem using "inc dptr".

I my display work, basically I get by with everything in C except feeding the display which is in assembler.

Erik