I have been using plot and plot text functions to fulfill my needs of plotting trade info and arrows etc while live trading. Have been wondering if i shift to low level graphics instead , will that have impact on performance of my live systems in terms being slow to refresh etc..?
For plotting arrays there is not anything that beats Plot() function.
So from speed perspective it makes no sense to replace it by multiple lines of Gfx code doing the same thing (if that is your intention as your quote says "...shift to low level graphics instead"). Then the answer is... no, rather do not do that. Well, of course nobody prohibits you to do it anyway (since you are free man, I suppose) but at least you should be aware that you will not be able to beat Plot() timings and small amount of code being required.
Gfx functions make more sense for plotting things that are not readily available or not doable via other inbuilt features (so e.g. Gfx are more suitable for drawing tables in chart panes, statistical plots, 3D, profiles, chart trading features, etc, etc).
Also it makes more sense to use Gfx for plotting single lines. Then as T.J once pointed out Gfx* are faster than Plot().