On some of the really common older plotter models, like the 74xx/75xx, these features were present but it's often desirable to not use them as the plotter linea

On some of the really common older plotter models, like the 74xx/75xx, these features were present but it's often desirable to not use them as the plotter linearizes curve segments much more slowly than the host computer can. So you'll get markedly faster plotting (and less inconsistent ink bleed) if you reduce everything to line segments on the host. This can be as much as a 90% improvement in plotting speed if you have the linearization set pretty high (which is default a startup). And at least on the 74xx, I have never experienced out-of-order execution of instructions, I'm skeptical that any plotters other than very recently implemented this as it would break assumptions made by a number of plotting packages if the plotter executed out of order. Many HPGL commands are highly stateful, considering how slow the on-board processor on these plotters was it'd probably make them net slower if they even tried to optimize. The buffer is also very small in 'compatibility mode' but modern packages should be fine with the 'extended' buffer size that can sometimes fit a whole document if it's not too complex.