Well the 6502 didn't have many registers but the CPU and SRAM were of similar speed back then so most of the temporary values were stored in SRAM. Not too long

Well the 6502 didn't have many registers but the CPU and SRAM were of similar speed back then so most of the temporary values were stored in SRAM. Not too long ago I did firmware on an 8-bit processor using the C language. It would support 32/16/8-bit variables. You just have to choose the smallest one possible to be most efficient.