First thing:
If a code functions there are no reasons to change it.
Second thing:
You can do a function where you pass the number you have to write on the display and it writes that number. Like
void Writenumber(int number)
{
if (number<10)
{
//write '0'
}
//write number
return
}
I don't know if you can cut any libraries, because I think they are all used by components you are using. You can try cut any library by commenting its inclusion, if the program works everyway you done. You can cut the inclusion of arduinomh, that is automatically included (i think) by the compiler.
For ways to reduce times I think there aren't, not witch the same component.